linux驱动移植-usb主机控制器驱动

struct usb_hcd {

        /*
         * housekeeping
         */
        struct usb_bus          self;           /* hcd is-a bus */
        struct kref             kref;           /* reference counter */

        const char              *product_desc;  /* product/vendor string */
        int                     speed;          /* Speed for this roothub.
                                                 * May be different from
                                                 * hcd->driver->flags & HCD_MASK
                                                 */
        char                    irq_descr[24];  /* driver + bus # */

        struct timer_list       rh_timer;       /* drives root-hub polling */
        struct urb              *status_urb;    /* the current status urb */
#ifdef CONFIG_PM
        struct work_struct      wakeup_work;    /* for remote wakeup */
#endif
        struct work_struct      died_work;      /* for when the device dies */

        /*
         * hardware info/state
         */
        const struct hc_driver  *driver;        /* hw-specific hooks */

        /*
         * OTG and some Host controllers need software interaction with phys;
         * other external phys should be software-transparent
         */
        struct usb_phy          *usb_phy;
        struct usb_phy_roothub  *phy_roothub;

        /* Flags that need to be manipulated atomically because they can
         * change while the host controller is running.  Always use
         * set_bit() or clear_bit() to change their values.
         */
        unsigned long           flags;
#define HCD_FLAG_HW_ACCESSIBLE          0       /* at full power */
#define HCD_FLAG_POLL_RH                2       /* poll for rh status? */
#define HCD_FLAG_POLL_PENDING           3       /* status has changed? */
#define HCD_FLAG_WAKEUP_PENDING         4       /* root hub is resuming? */
#define HCD_FLAG_RH_RUNNING             5       /* root hub is running? */
#define HCD_FLAG_DEAD                   6       /* controller has died? */
#define HCD_FLAG_INTF_AUTHORIZED        7       /* authorize interfaces? */

        /* The flags can be tested using these macros; they are likely to
         * be slightly faster than test_bit().
         */
#define HCD_HW_ACCESSIBLE(hcd)  ((hcd)->flags & (1U << HCD_FLAG_HW_ACCESSIBLE))
#define HCD_POLL_RH(hcd)        ((hcd)->flags & (1U << HCD_FLAG_POLL_RH))
#define HCD_POLL_PENDING(hcd)   ((hcd)->flags & (1U << HCD_FLAG_POLL_PENDING))
#define HCD_WAKEUP_PENDING(hcd) ((hcd)->flags & (1U << HCD_FLAG_WAKEUP_PENDING))
#define HCD_RH_RUNNING(hcd)     ((hcd)->flags & (1U << HCD_FLAG_RH_RUNNING))
#define HCD_DEAD(hcd)           ((hcd)->flags & (1U << HCD_FLAG_DEAD))
 /*
         * Specifies if interfaces are authorized by default
         * or they require explicit user space authorization; this bit is
         * settable through /sys/class/usb_host/X/interface_authorized_default
         */
#define HCD_INTF_AUTHORIZED(hcd) 
        ((hcd)->flags & (1U << HCD_FLAG_INTF_AUTHORIZED))

        /*
         * Specifies if devices are authorized by default
         * or they require explicit user space authorization; this bit is
         * settable through /sys/class/usb_host/X/authorized_default
         */
        enum usb_dev_authorize_policy dev_policy;

        /* Flags that get set only during HCD registration or removal. */
        unsigned                rh_registered:1;/* is root hub registered? */
        unsigned                rh_pollable:1;  /* may we poll the root hub? */
        unsigned                msix_enabled:1; /* driver has MSI-X enabled? */
        unsigned                msi_enabled:1;  /* driver has MSI enabled? */
        /*
         * do not manage the PHY state in the HCD core, instead let the driver
         * handle this (for example if the PHY can only be turned on after a
         * specific event)
         */
        unsigned                skip_phy_initialization:1;

        /* The next flag is a stopgap, to be removed when all the HCDs
         * support the new root-hub polling mechanism. */
        unsigned                uses_new_polling:1;
        unsigned                wireless:1;     /* Wireless USB HCD */
        unsigned                has_tt:1;       /* Integrated TT in root hub */
        unsigned                amd_resume_bug:1; /* AMD remote wakeup quirk */
        unsigned                can_do_streams:1; /* HC supports streams */
        unsigned                tpl_support:1; /* OTG & EH TPL support */
        unsigned                cant_recv_wakeups:1;
                        /* wakeup requests from downstream aren't received */

        unsigned int            irq;            /* irq allocated */
        void __iomem            *regs;          /* device memory/io */
        resource_size_t         rsrc_start;     /* memory/io resource start */
        resource_size_t         rsrc_len;       /* memory/io resource length */
        unsigned                power_budget;   /* in mA, 0 = no limit */

        struct giveback_urb_bh  high_prio_bh;
        struct giveback_urb_bh  low_prio_bh;

        /* bandwidth_mutex should be taken before adding or removing
         * any new bus bandwidth constraints:
         *   1. Before adding a configuration for a new device.
         *   2. Before removing the configuration to put the device into
         *      the addressed state.
         *   3. Before selecting a different configuration.
         *   4. Before selecting an alternate interface setting.
         *
         * bandwidth_mutex should be dropped after a successful control message
         * to the device, or resetting the bandwidth after a failed attempt.
         */
 struct mutex            *address0_mutex;
        struct mutex            *bandwidth_mutex;
        struct usb_hcd          *shared_hcd;
        struct usb_hcd          *primary_hcd;


#define HCD_BUFFER_POOLS        4
        struct dma_pool         *pool[HCD_BUFFER_POOLS];

        int                     state;
#       define  __ACTIVE                0x01
#       define  __SUSPEND               0x04
#       define  __TRANSIENT             0x80

#       define  HC_STATE_HALT           0
#       define  HC_STATE_RUNNING        (__ACTIVE)
#       define  HC_STATE_QUIESCING      (__SUSPEND|__TRANSIENT|__ACTIVE)
#       define  HC_STATE_RESUMING       (__SUSPEND|__TRANSIENT)
#       define  HC_STATE_SUSPENDED      (__SUSPEND)

#define HC_IS_RUNNING(state) ((state) & __ACTIVE)
#define HC_IS_SUSPENDED(state) ((state) & __SUSPEND)

        /* more shared queuing code would be good; it should support
         * smarter scheduling, handle transaction translators, etc;
         * input size of periodic table to an interrupt scheduler.
         * (ohci 32, uhci 1024, ehci 256/512/1024).
         */

        /* The HC driver's private data is stored at the end of
         * this structure.
         */
        unsigned long hcd_priv[0]
                        __attribute__ ((aligned(sizeof(s64))));
};

/*
 * Allocated per bus (tree of devices) we have:
 */
struct usb_bus {
        struct device *controller;      /* host/master side hardware */
        struct device *sysdev;          /* as seen from firmware or bus */
        int busnum;                     /* Bus number (in order of reg) */
        const char *bus_name;           /* stable id (PCI slot_name etc) */
        u8 uses_dma;                    /* Does the host controller use DMA? */
        u8 uses_pio_for_control;        /*
                                         * Does the host controller use PIO
                                         * for control transfers?
                                         */
        u8 otg_port;                    /* 0, or number of OTG/HNP port */
        unsigned is_b_host:1;           /* true during some HNP roleswitches */
        unsigned b_hnp_enable:1;        /* OTG: did A-Host enable HNP? */
        unsigned no_stop_on_short:1;    /*
                                         * Quirk: some controllers don't stop
                                         * the ep queue on a short transfer
                                         * with the URB_SHORT_NOT_OK flag set.
                                         */
        unsigned no_sg_constraint:1;    /* no sg constraint */
        unsigned sg_tablesize;          /* 0 or largest number of sg list entries */

        int devnum_next;                /* Next open device number in
                                         * round-robin allocation */
        struct mutex devnum_next_mutex; /* devnum_next mutex */

        struct usb_devmap devmap;       /* device address allocation map */
        struct usb_device *root_hub;    /* Root hub */
        struct usb_bus *hs_companion;   /* Companion EHCI bus, if any */

        int bandwidth_allocated;        /* on this bus: how much of the time
                                         * reserved for periodic (intr/iso)
                                         * requests is used, on average?
                                         * Units: microseconds/frame.
                                         * Limits: Full/low speed reserve 90%,
                                         * while high speed reserves 80%.
                                         */
        int bandwidth_int_reqs;         /* number of Interrupt requests */
        int bandwidth_isoc_reqs;        /* number of Isoc. requests */

        unsigned resuming_ports;        /* bit array: resuming root-hub ports */

#if defined(CONFIG_USB_MON) || defined(CONFIG_USB_MON_MODULE)
        struct mon_bus *mon_bus;        /* non-null when associated */
        int monitored;                  /* non-zero when monitored */
#endif
};

struct hc_driver {
        const char      *description;   /* "ehci-hcd" etc */
        const char      *product_desc;  /* product/vendor string */
        size_t          hcd_priv_size;  /* size of private data */

        /* irq handler */
        irqreturn_t     (*irq) (struct usb_hcd *hcd);

        int     flags;
#define HCD_MEMORY      0x0001          /* HC regs use memory (else I/O) */
#define HCD_LOCAL_MEM   0x0002          /* HC needs local memory */
#define HCD_SHARED      0x0004          /* Two (or more) usb_hcds share HW */
#define HCD_USB11       0x0010          /* USB 1.1 */
#define HCD_USB2        0x0020          /* USB 2.0 */
#define HCD_USB25       0x0030          /* Wireless USB 1.0 (USB 2.5)*/
#define HCD_USB3        0x0040          /* USB 3.0 */
#define HCD_USB31       0x0050          /* USB 3.1 */
#define HCD_USB32       0x0060          /* USB 3.2 */
#define HCD_MASK        0x0070
#define HCD_BH          0x0100          /* URB complete in BH context */

        /* called to init HCD and root hub */
        int     (*reset) (struct usb_hcd *hcd);
        int     (*start) (struct usb_hcd *hcd);

        /* NOTE:  these suspend/resume calls relate to the HC as
         * a whole, not just the root hub; they're for PCI bus glue.
         */
        /* called after suspending the hub, before entering D3 etc */
        int     (*pci_suspend)(struct usb_hcd *hcd, bool do_wakeup);

        /* called after entering D0 (etc), before resuming the hub */
        int     (*pci_resume)(struct usb_hcd *hcd, bool hibernated);

        /* cleanly make HCD stop writing memory and doing I/O */
        void    (*stop) (struct usb_hcd *hcd);

        /* shutdown HCD */
        void    (*shutdown) (struct usb_hcd *hcd);

        /* return current frame number */
        int     (*get_frame_number) (struct usb_hcd *hcd);

        /* manage i/o requests, device state */
        int     (*urb_enqueue)(struct usb_hcd *hcd,
                                struct urb *urb, gfp_t mem_flags);
        int     (*urb_dequeue)(struct usb_hcd *hcd,
                                struct urb *urb, int status);

 /*
         * (optional) these hooks allow an HCD to override the default DMA
         * mapping and unmapping routines.  In general, they shouldn't be
         * necessary unless the host controller has special DMA requirements,
         * such as alignment contraints.  If these are not specified, the
         * general usb_hcd_(un)?map_urb_for_dma functions will be used instead
         * (and it may be a good idea to call these functions in your HCD
         * implementation)
         */
        int     (*map_urb_for_dma)(struct usb_hcd *hcd, struct urb *urb,
                                   gfp_t mem_flags);
        void    (*unmap_urb_for_dma)(struct usb_hcd *hcd, struct urb *urb);

        /* hw synch, freeing endpoint resources that urb_dequeue can't */
        void    (*endpoint_disable)(struct usb_hcd *hcd,
                        struct usb_host_endpoint *ep);

        /* (optional) reset any endpoint state such as sequence number
           and current window */
        void    (*endpoint_reset)(struct usb_hcd *hcd,
                        struct usb_host_endpoint *ep);

        /* root hub support */
        int     (*hub_status_data) (struct usb_hcd *hcd, char *buf);
        int     (*hub_control) (struct usb_hcd *hcd,
                                u16 typeReq, u16 wValue, u16 wIndex,
                                char *buf, u16 wLength);
        int     (*bus_suspend)(struct usb_hcd *);
        int     (*bus_resume)(struct usb_hcd *);
        int     (*start_port_reset)(struct usb_hcd *, unsigned port_num);
        unsigned long   (*get_resuming_ports)(struct usb_hcd *);

                /* force handover of high-speed port to full-speed companion */
        void    (*relinquish_port)(struct usb_hcd *, int);
                /* has a port been handed over to a companion? */
        int     (*port_handed_over)(struct usb_hcd *, int);

                /* CLEAR_TT_BUFFER completion callback */
        void    (*clear_tt_buffer_complete)(struct usb_hcd *,
                                struct usb_host_endpoint *);

        /* xHCI specific functions */
                /* Called by usb_alloc_dev to alloc HC device structures */
        int     (*alloc_dev)(struct usb_hcd *, struct usb_device *);
                /* Called by usb_disconnect to free HC device structures */
        void    (*free_dev)(struct usb_hcd *, struct usb_device *);
        /* Change a group of bulk endpoints to support multiple stream IDs */
        int     (*alloc_streams)(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint **eps, unsigned int num_eps,
                unsigned int num_streams, gfp_t mem_flags);
        /* Reverts a group of bulk endpoints back to not using stream IDs.
         * Can fail if we run out of memory.
         */
        int     (*free_streams)(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint **eps, unsigned int num_eps,
                gfp_t mem_flags);
 /* Bandwidth computation functions */
        /* Note that add_endpoint() can only be called once per endpoint before
         * check_bandwidth() or reset_bandwidth() must be called.
         * drop_endpoint() can only be called once per endpoint also.
         * A call to xhci_drop_endpoint() followed by a call to
         * xhci_add_endpoint() will add the endpoint to the schedule with
         * possibly new parameters denoted by a different endpoint descriptor
         * in usb_host_endpoint.  A call to xhci_add_endpoint() followed by a
         * call to xhci_drop_endpoint() is not allowed.
         */
                /* Allocate endpoint resources and add them to a new schedule */
        int     (*add_endpoint)(struct usb_hcd *, struct usb_device *,
                                struct usb_host_endpoint *);
                /* Drop an endpoint from a new schedule */
        int     (*drop_endpoint)(struct usb_hcd *, struct usb_device *,
                                 struct usb_host_endpoint *);
                /* Check that a new hardware configuration, set using
                 * endpoint_enable and endpoint_disable, does not exceed bus
                 * bandwidth.  This must be called before any set configuration
                 * or set interface requests are sent to the device.
                 */
        int     (*check_bandwidth)(struct usb_hcd *, struct usb_device *);
                /* Reset the device schedule to the last known good schedule,
                 * which was set from a previous successful call to
                 * check_bandwidth().  This reverts any add_endpoint() and
                 * drop_endpoint() calls since that last successful call.
                 * Used for when a check_bandwidth() call fails due to resource
                 * or bandwidth constraints.
                 */
        void    (*reset_bandwidth)(struct usb_hcd *, struct usb_device *);
                /* Returns the hardware-chosen device address */
        int     (*address_device)(struct usb_hcd *, struct usb_device *udev);
                /* prepares the hardware to send commands to the device */
        int     (*enable_device)(struct usb_hcd *, struct usb_device *udev);
                /* Notifies the HCD after a hub descriptor is fetched.
                 * Will block.
                 */
        int     (*update_hub_device)(struct usb_hcd *, struct usb_device *hdev,
                        struct usb_tt *tt, gfp_t mem_flags);
        int     (*reset_device)(struct usb_hcd *, struct usb_device *);
                /* Notifies the HCD after a device is connected and its
                 * address is set
                 */
        int     (*update_device)(struct usb_hcd *, struct usb_device *);
        int     (*set_usb2_hw_lpm)(struct usb_hcd *, struct usb_device *, int);
        /* USB 3.0 Link Power Management */
                /* Returns the USB3 hub-encoded value for the U1/U2 timeout. */
        int     (*enable_usb3_lpm_timeout)(struct usb_hcd *,
                        struct usb_device *, enum usb3_link_state state);
                /* The xHCI host controller can still fail the command to
                 * disable the LPM timeouts, so this can return an error code.
                 */
        int     (*disable_usb3_lpm_timeout)(struct usb_hcd *,
                        struct usb_device *, enum usb3_link_state state);
        int     (*find_raw_port_number)(struct usb_hcd *, int);
        /* Call for power on/off the port if necessary */
        int     (*port_power)(struct usb_hcd *hcd, int portnum, bool enable);

};

/*
 * Get the USB config descriptors, cache and parse'em
 *
 * hub-only!! ... and only in reset path, or usb_new_device()
 * (used by real hubs and virtual root hubs)
 */
int usb_get_configuration(struct usb_device *dev)
{
        struct device *ddev = &dev->dev;
        int ncfg = dev->descriptor.bNumConfigurations;
        int result = -ENOMEM;
        unsigned int cfgno, length;
        unsigned char *bigbuffer;
        struct usb_config_descriptor *desc;

        if (ncfg > USB_MAXCONFIG) {
                dev_warn(ddev, "too many configurations: %d, "
                    "using maximum allowed: %dn", ncfg, USB_MAXCONFIG);
                dev->descriptor.bNumConfigurations = ncfg = USB_MAXCONFIG;
        }

        if (ncfg < 1) {
                dev_err(ddev, "no configurationsn");
                return -EINVAL;
        }

        length = ncfg * sizeof(struct usb_host_config);
        dev->config = kzalloc(length, GFP_KERNEL);
        if (!dev->config)
                goto err2;

        length = ncfg * sizeof(char *);
        dev->rawdescriptors = kzalloc(length, GFP_KERNEL);
        if (!dev->rawdescriptors)
                goto err2;

        desc = kmalloc(USB_DT_CONFIG_SIZE, GFP_KERNEL);
        if (!desc)
                goto err2;

        for (cfgno = 0; cfgno < ncfg; cfgno++) {
                /* We grab just the first descriptor so we know how long
                 * the whole configuration is */
                result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
                    desc, USB_DT_CONFIG_SIZE);
                if (result < 0) {
                        dev_err(ddev, "unable to read config index %d "
                            "descriptor/%s: %dn", cfgno, "start", result);
                        if (result != -EPIPE)
                                goto err;
                        dev_err(ddev, "chopping to %d config(s)n", cfgno);
                        dev->descriptor.bNumConfigurations = cfgno;
                        break;
                } else if (result < 4) {
                        dev_err(ddev, "config index %d descriptor too short "
                            "(expected %i, got %i)n", cfgno,
                            USB_DT_CONFIG_SIZE, result);
                        result = -EINVAL;
                        goto err;
                }
                length = max((int) le16_to_cpu(desc->wTotalLength),
                    USB_DT_CONFIG_SIZE);

                /* Now that we know the length, get the whole thing */
                bigbuffer = kmalloc(length, GFP_KERNEL);
                if (!bigbuffer) {
                        result = -ENOMEM;
                        goto err;
 }

                if (dev->quirks & USB_QUIRK_DELAY_INIT)
                        msleep(200);

                result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
                    bigbuffer, length);
                if (result < 0) {
                        dev_err(ddev, "unable to read config index %d "
                            "descriptor/%sn", cfgno, "all");
                        kfree(bigbuffer);
                        goto err;
                }
                if (result < length) {
                        dev_warn(ddev, "config index %d descriptor too short "
                            "(expected %i, got %i)n", cfgno, length, result);
                        length = result;
                }

                dev->rawdescriptors[cfgno] = bigbuffer;

                result = usb_parse_configuration(dev, cfgno,
                    &dev->config[cfgno], bigbuffer, length);
                if (result < 0) {
                        ++cfgno;
                        goto err;
                }
        }

err:
        kfree(desc);
        dev->descriptor.bNumConfigurations = cfgno;
err2:
        if (result == -ENOMEM)
                dev_err(ddev, "out of memoryn");
        return result;
}

static int hub_configure(struct usb_hub *hub,
        struct usb_endpoint_descriptor *endpoint)
{
        struct usb_hcd *hcd;
        struct usb_device *hdev = hub->hdev;
        struct device *hub_dev = hub->intfdev;
        u16 hubstatus, hubchange;
        u16 wHubCharacteristics;
        unsigned int pipe;
        int maxp, ret, i;
        char *message = "out of memory";
        unsigned unit_load;
        unsigned full_load;
        unsigned maxchild;

        hub->buffer = kmalloc(sizeof(*hub->buffer), GFP_KERNEL);
        if (!hub->buffer) {
                ret = -ENOMEM;
                goto fail;
        }

        hub->status = kmalloc(sizeof(*hub->status), GFP_KERNEL);
        if (!hub->status) {
                ret = -ENOMEM;
                goto fail;
        }
        mutex_init(&hub->status_mutex);

        hub->descriptor = kzalloc(sizeof(*hub->descriptor), GFP_KERNEL);
        if (!hub->descriptor) {
                ret = -ENOMEM;
                goto fail;
        }

        /* Request the entire hub descriptor.
         * hub->descriptor can handle USB_MAXCHILDREN ports,
         * but a (non-SS) hub can/will return fewer bytes here.
         */
        ret = get_hub_descriptor(hdev, hub->descriptor);
        if (ret < 0) {
                message = "can't read hub descriptor";
                goto fail;
        }

        maxchild = USB_MAXCHILDREN;
        if (hub_is_superspeed(hdev))
                maxchild = min_t(unsigned, maxchild, USB_SS_MAXPORTS);

        if (hub->descriptor->bNbrPorts > maxchild) {
                message = "hub has too many ports!";
                ret = -ENODEV;
                goto fail;
        } else if (hub->descriptor->bNbrPorts == 0) {
                message = "hub doesn't have any ports!";
                ret = -ENODEV;
                goto fail;
        }
 /*
         * Accumulate wHubDelay + 40ns for every hub in the tree of devices.
         * The resulting value will be used for SetIsochDelay() request.
         */
        if (hub_is_superspeed(hdev) || hub_is_superspeedplus(hdev)) {
                u32 delay = __le16_to_cpu(hub->descriptor->u.ss.wHubDelay);

                if (hdev->parent)
                        delay += hdev->parent->hub_delay;

                delay += USB_TP_TRANSMISSION_DELAY;
                hdev->hub_delay = min_t(u32, delay, USB_TP_TRANSMISSION_DELAY_MAX);
        }

        maxchild = hub->descriptor->bNbrPorts;
        dev_info(hub_dev, "%d port%s detectedn", maxchild,
                        (maxchild == 1) ? "" : "s");

        hub->ports = kcalloc(maxchild, sizeof(struct usb_port *), GFP_KERNEL);
        if (!hub->ports) {
                ret = -ENOMEM;
                goto fail;
        }

        wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);
        if (hub_is_superspeed(hdev)) {
                unit_load = 150;
                full_load = 900;
        } else {
                unit_load = 100;
                full_load = 500;
        }

        /* FIXME for USB 3.0, skip for now */
        if ((wHubCharacteristics & HUB_CHAR_COMPOUND) &&
                        !(hub_is_superspeed(hdev))) {
                char    portstr[USB_MAXCHILDREN + 1];

                for (i = 0; i < maxchild; i++)
                        portstr[i] = hub->descriptor->u.hs.DeviceRemovable
                                    [((i + 1) / 8)] & (1 << ((i + 1) % 8))
                                ? 'F' : 'R';
                portstr[maxchild] = 0;
                dev_dbg(hub_dev, "compound device; port removable status: %sn", portstr);
        } else
                dev_dbg(hub_dev, "standalone hubn");

        switch (wHubCharacteristics & HUB_CHAR_LPSM) {
        case HUB_CHAR_COMMON_LPSM:
                dev_dbg(hub_dev, "ganged power switchingn");
                break;
        case HUB_CHAR_INDV_PORT_LPSM:
                dev_dbg(hub_dev, "individual port power switchingn");
                break;
        case HUB_CHAR_NO_LPSM:
        case HUB_CHAR_LPSM:
                dev_dbg(hub_dev, "no power switching (usb 1.0)n");
                break;
        }

        switch (wHubCharacteristics & HUB_CHAR_OCPM) {
        case HUB_CHAR_COMMON_OCPM:
                dev_dbg(hub_dev, "global over-current protectionn");
                break;
        case HUB_CHAR_INDV_PORT_OCPM:
                dev_dbg(hub_dev, "individual port over-current protectionn");
                break;
        case HUB_CHAR_NO_OCPM:
        case HUB_CHAR_OCPM:
                dev_dbg(hub_dev, "no over-current protectionn");
                break;
        }
 spin_lock_init(&hub->tt.lock);
        INIT_LIST_HEAD(&hub->tt.clear_list);
        INIT_WORK(&hub->tt.clear_work, hub_tt_work);
        switch (hdev->descriptor.bDeviceProtocol) {
        case USB_HUB_PR_FS:
                break;
        case USB_HUB_PR_HS_SINGLE_TT:
                dev_dbg(hub_dev, "Single TTn");
                hub->tt.hub = hdev;
                break;
        case USB_HUB_PR_HS_MULTI_TT:
                ret = usb_set_interface(hdev, 0, 1);
                if (ret == 0) {
                        dev_dbg(hub_dev, "TT per portn");
                        hub->tt.multi = 1;
                } else
                        dev_err(hub_dev, "Using single TT (err %d)n",
                                ret);
                hub->tt.hub = hdev;
                break;
        case USB_HUB_PR_SS:
                /* USB 3.0 hubs don't have a TT */
                break;
        default:
                dev_dbg(hub_dev, "Unrecognized hub protocol %dn",
                        hdev->descriptor.bDeviceProtocol);
                break;
        }

        /* Note 8 FS bit times == (8 bits / 12000000 bps) ~= 666ns */
        switch (wHubCharacteristics & HUB_CHAR_TTTT) {
        case HUB_TTTT_8_BITS:
                if (hdev->descriptor.bDeviceProtocol != 0) {
                        hub->tt.think_time = 666;
                        dev_dbg(hub_dev, "TT requires at most %d "
                                        "FS bit times (%d ns)n",
                                8, hub->tt.think_time);
                }
                break;
        case HUB_TTTT_16_BITS:
                hub->tt.think_time = 666 * 2;
                dev_dbg(hub_dev, "TT requires at most %d "
                                "FS bit times (%d ns)n",
                        16, hub->tt.think_time);
                break;
        case HUB_TTTT_24_BITS:
                hub->tt.think_time = 666 * 3;
                dev_dbg(hub_dev, "TT requires at most %d "
                                "FS bit times (%d ns)n",
                        24, hub->tt.think_time);
                break;
        case HUB_TTTT_32_BITS:
                hub->tt.think_time = 666 * 4;
                dev_dbg(hub_dev, "TT requires at most %d "
                                "FS bit times (%d ns)n",
                        32, hub->tt.think_time);
                break;
        }

        /* probe() zeroes hub->indicator[] */
        if (wHubCharacteristics & HUB_CHAR_PORTIND) {
                hub->has_indicators = 1;
                dev_dbg(hub_dev, "Port indicators are supportedn");
        }

        dev_dbg(hub_dev, "power on to power good time: %dmsn",
                hub->descriptor->bPwrOn2PwrGood * 2);
 /* power budgeting mostly matters with bus-powered hubs,
         * and battery-powered root hubs (may provide just 8 mA).
         */
        ret = usb_get_std_status(hdev, USB_RECIP_DEVICE, 0, &hubstatus);
        if (ret) {
                message = "can't get hub status";
                goto fail;
        }
        hcd = bus_to_hcd(hdev->bus);
        if (hdev == hdev->bus->root_hub) {
                if (hcd->power_budget > 0)
                        hdev->bus_mA = hcd->power_budget;
                else
                        hdev->bus_mA = full_load * maxchild;
                if (hdev->bus_mA >= full_load)
                        hub->mA_per_port = full_load;
                else {
                        hub->mA_per_port = hdev->bus_mA;
                        hub->limited_power = 1;
                }
        } else if ((hubstatus & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
                int remaining = hdev->bus_mA -
                        hub->descriptor->bHubContrCurrent;

                dev_dbg(hub_dev, "hub controller current requirement: %dmAn",
                        hub->descriptor->bHubContrCurrent);
                hub->limited_power = 1;

                if (remaining < maxchild * unit_load)
                        dev_warn(hub_dev,
                                        "insufficient power available "
                                        "to use all downstream portsn");
                hub->mA_per_port = unit_load;   /* 7.2.1 */

        } else {        /* Self-powered external hub */
                /* FIXME: What about battery-powered external hubs that
                 * provide less current per port? */
                hub->mA_per_port = full_load;
        }
        if (hub->mA_per_port < full_load)
                dev_dbg(hub_dev, "%umA bus power budget for each childn",
                                hub->mA_per_port);

        ret = hub_hub_status(hub, &hubstatus, &hubchange);
        if (ret < 0) {
                message = "can't get hub status";
                goto fail;
        }

        /* local power status reports aren't always correct */
        if (hdev->actconfig->desc.bmAttributes & USB_CONFIG_ATT_SELFPOWER)
                dev_dbg(hub_dev, "local power source is %sn",
                        (hubstatus & HUB_STATUS_LOCAL_POWER)
                        ? "lost (inactive)" : "good");

        if ((wHubCharacteristics & HUB_CHAR_OCPM) == 0)
                dev_dbg(hub_dev, "%sover-current condition existsn",
                        (hubstatus & HUB_STATUS_OVERCURRENT) ? "" : "no ");
 /* set up the interrupt endpoint
         * We use the EP's maxpacket size instead of (PORTS+1+7)/8
         * bytes as USB2.0[11.12.3] says because some hubs are known
         * to send more data (and thus cause overflow). For root hubs,
         * maxpktsize is defined in hcd.c's fake endpoint descriptors
         * to be big enough for at least USB_MAXCHILDREN ports. */
        pipe = usb_rcvintpipe(hdev, endpoint->bEndpointAddress);
        maxp = usb_maxpacket(hdev, pipe, usb_pipeout(pipe));

        if (maxp > sizeof(*hub->buffer))
                maxp = sizeof(*hub->buffer);

        hub->urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!hub->urb) {
                ret = -ENOMEM;
                goto fail;
        }

        usb_fill_int_urb(hub->urb, hdev, pipe, *hub->buffer, maxp, hub_irq,
                hub, endpoint->bInterval);

        /* maybe cycle the hub leds */
        if (hub->has_indicators && blinkenlights)
                hub->indicator[0] = INDICATOR_CYCLE;

        mutex_lock(&usb_port_peer_mutex);
        for (i = 0; i < maxchild; i++) {
                ret = usb_hub_create_port_device(hub, i + 1);
                if (ret < 0) {
                        dev_err(hub->intfdev,
                                "couldn't create port%d device.n", i + 1);
                        break;
                }
        }
        hdev->maxchild = i;
        for (i = 0; i < hdev->maxchild; i++) {
                struct usb_port *port_dev = hub->ports[i];

                pm_runtime_put(&port_dev->dev);
        }

        mutex_unlock(&usb_port_peer_mutex);
        if (ret < 0)
                goto fail;

        /* Update the HCD's internal representation of this hub before hub_wq
         * starts getting port status changes for devices under the hub.
         */
        if (hcd->driver->update_hub_device) {
                ret = hcd->driver->update_hub_device(hcd, hdev,
                                &hub->tt, GFP_KERNEL);
                if (ret < 0) {
                        message = "can't update HCD hub info";
                        goto fail;
                }
        }

        usb_hub_adjust_deviceremovable(hdev, hub->descriptor);

        hub_activate(hub, HUB_INIT);
        return 0;

fail:
        dev_err(hub_dev, "config failed, %s (err %d)n",
                        message, ret);
        /* hub_disconnect() frees urb and descriptor */
        return ret;
}

/**
 * usb_fill_int_urb - macro to help initialize a interrupt urb
 * @urb: pointer to the urb to initialize.
 * @dev: pointer to the struct usb_device for this urb.
 * @pipe: the endpoint pipe
 * @transfer_buffer: pointer to the transfer buffer
 * @buffer_length: length of the transfer buffer
 * @complete_fn: pointer to the usb_complete_t function
 * @context: what to set the urb context to.
 * @interval: what to set the urb interval to, encoded like
 *      the endpoint descriptor's bInterval value.
 *
 * Initializes a interrupt urb with the proper information needed to submit
 * it to a device.
 *
 * Note that High Speed and SuperSpeed(+) interrupt endpoints use a logarithmic
 * encoding of the endpoint interval, and express polling intervals in
 * microframes (eight per millisecond) rather than in frames (one per
 * millisecond).
 *
 * Wireless USB also uses the logarithmic encoding, but specifies it in units of
 * 128us instead of 125us.  For Wireless USB devices, the interval is passed
 * through to the host controller, rather than being translated into microframe
 * units.
 */
static inline void usb_fill_int_urb(struct urb *urb,
                                    struct usb_device *dev,
                                    unsigned int pipe,
                                    void *transfer_buffer,
                                    int buffer_length,
                                    usb_complete_t complete_fn,
                                    void *context,
                                    int interval)
{
        urb->dev = dev;
        urb->pipe = pipe;
        urb->transfer_buffer = transfer_buffer;
        urb->transfer_buffer_length = buffer_length;
        urb->complete = complete_fn;
        urb->context = context;

        if (dev->speed == USB_SPEED_HIGH || dev->speed >= USB_SPEED_SUPER) {
                /* make sure interval is within allowed range */
                interval = clamp(interval, 1, 16);

                urb->interval = 1 << (interval - 1);
        } else {
                urb->interval = interval;
        }

        urb->start_frame = -1;
}

static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
{
        struct usb_device *hdev = hub->hdev;
        struct usb_hcd *hcd;
        int ret;
        int port1;
        int status;
        bool need_debounce_delay = false;
        unsigned delay;

        /* Continue a partial initialization */
        if (type == HUB_INIT2 || type == HUB_INIT3) {
                device_lock(&hdev->dev);

                /* Was the hub disconnected while we were waiting? */
                if (hub->disconnected)
                        goto disconnected;
                if (type == HUB_INIT2)
                        goto init2;
                goto init3;
        }
        kref_get(&hub->kref);

        /* The superspeed hub except for root hub has to use Hub Depth
         * value as an offset into the route string to locate the bits
         * it uses to determine the downstream port number. So hub driver
         * should send a set hub depth request to superspeed hub after
         * the superspeed hub is set configuration in initialization or
         * reset procedure.
         *
         * After a resume, port power should still be on.
         * For any other type of activation, turn it on.
         */
        if (type != HUB_RESUME) {
                if (hdev->parent && hub_is_superspeed(hdev)) {
                        ret = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                                        HUB_SET_DEPTH, USB_RT_HUB,
                                        hdev->level - 1, 0, NULL, 0,
                                        USB_CTRL_SET_TIMEOUT);
                        if (ret < 0)
                                dev_err(hub->intfdev,
                                                "set hub depth failedn");
                }
 /* Speed up system boot by using a delayed_work for the
                 * hub's initial power-up delays.  This is pretty awkward
                 * and the implementation looks like a home-brewed sort of
                 * setjmp/longjmp, but it saves at least 100 ms for each
                 * root hub (assuming usbcore is compiled into the kernel
                 * rather than as a module).  It adds up.
                 *
                 * This can't be done for HUB_RESUME or HUB_RESET_RESUME
                 * because for those activation types the ports have to be
                 * operational when we return.  In theory this could be done
                 * for HUB_POST_RESET, but it's easier not to.
                 */
                if (type == HUB_INIT) {
                        delay = hub_power_on_good_delay(hub);

                        hub_power_on(hub, false);
                        INIT_DELAYED_WORK(&hub->init_work, hub_init_func2);
                        queue_delayed_work(system_power_efficient_wq,
                                        &hub->init_work,
                                        msecs_to_jiffies(delay));

                        /* Suppress autosuspend until init is done */
                        usb_autopm_get_interface_no_resume(
                                        to_usb_interface(hub->intfdev));
                        return;         /* Continues at init2: below */
                } else if (type == HUB_RESET_RESUME) {
                        /* The internal host controller state for the hub device
                         * may be gone after a host power loss on system resume.
                         * Update the device's info so the HW knows it's a hub.
                         */
                        hcd = bus_to_hcd(hdev->bus);
                        if (hcd->driver->update_hub_device) {
                                ret = hcd->driver->update_hub_device(hcd, hdev,
                                                &hub->tt, GFP_NOIO);
                                if (ret < 0) {
                                        dev_err(hub->intfdev,
                                                "Host not accepting hub info updaten");
                                        dev_err(hub->intfdev,
                                                "LS/FS devices and hubs may not work under this hubn");
                                }
                        }
                        hub_power_on(hub, true);
                } else {
                        hub_power_on(hub, true);
                }
  }
 init2:

        /*
         * Check each port and set hub->change_bits to let hub_wq know
         * which ports need attention.
         */
        for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
                struct usb_port *port_dev = hub->ports[port1 - 1];
                struct usb_device *udev = port_dev->child;
                u16 portstatus, portchange;

                portstatus = portchange = 0;
                status = hub_port_status(hub, port1, &portstatus, &portchange);
                if (status)
                        goto abort;

                if (udev || (portstatus & USB_PORT_STAT_CONNECTION))
                        dev_dbg(&port_dev->dev, "status %04x change %04xn",
                                        portstatus, portchange);

                /*
                 * After anything other than HUB_RESUME (i.e., initialization
                 * or any sort of reset), every port should be disabled.
                 * Unconnected ports should likewise be disabled (paranoia),
                 * and so should ports for which we have no usb_device.
                 */
                if ((portstatus & USB_PORT_STAT_ENABLE) && (
                                type != HUB_RESUME ||
                                !(portstatus & USB_PORT_STAT_CONNECTION) ||
                                !udev ||
                                udev->state == USB_STATE_NOTATTACHED)) {
                        /*
                         * USB3 protocol ports will automatically transition
                         * to Enabled state when detect an USB3.0 device attach.
                         * Do not disable USB3 protocol ports, just pretend
                         * power was lost
                         */
                        portstatus &= ~USB_PORT_STAT_ENABLE;
                        if (!hub_is_superspeed(hdev))
                                usb_clear_port_feature(hdev, port1,
                                                   USB_PORT_FEAT_ENABLE);
                }

                /* Make sure a warm-reset request is handled by port_event */
                if (type == HUB_RESUME &&
                    hub_port_warm_reset_required(hub, port1, portstatus))
                        set_bit(port1, hub->event_bits);

                /*
                 * Add debounce if USB3 link is in polling/link training state.
                 * Link will automatically transition to Enabled state after
                 * link training completes.
                 */
                if (hub_is_superspeed(hdev) &&
                    ((portstatus & USB_PORT_STAT_LINK_STATE) ==
                                                USB_SS_PORT_LS_POLLING))
                        need_debounce_delay = true;

                /* Clear status-change flags; we'll debounce later */
                if (portchange & USB_PORT_STAT_C_CONNECTION) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_CONNECTION);
                }
    if (portchange & USB_PORT_STAT_C_ENABLE) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_ENABLE);
                }
                if (portchange & USB_PORT_STAT_C_RESET) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_RESET);
                }
                if ((portchange & USB_PORT_STAT_C_BH_RESET) &&
                                hub_is_superspeed(hub->hdev)) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_BH_PORT_RESET);
                }
                /* We can forget about a "removed" device when there's a
                 * physical disconnect or the connect status changes.
                 */
                if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
                                (portchange & USB_PORT_STAT_C_CONNECTION))
                        clear_bit(port1, hub->removed_bits);

                if (!udev || udev->state == USB_STATE_NOTATTACHED) {
                        /* Tell hub_wq to disconnect the device or
                         * check for a new connection or over current condition.
                         * Based on USB2.0 Spec Section 11.12.5,
                         * C_PORT_OVER_CURRENT could be set while
                         * PORT_OVER_CURRENT is not. So check for any of them.
                         */
                        if (udev || (portstatus & USB_PORT_STAT_CONNECTION) ||
                            (portstatus & USB_PORT_STAT_OVERCURRENT) ||
                            (portchange & USB_PORT_STAT_C_OVERCURRENT))
                                set_bit(port1, hub->change_bits);

                } else if (portstatus & USB_PORT_STAT_ENABLE) {
                        bool port_resumed = (portstatus &
                                        USB_PORT_STAT_LINK_STATE) ==
                                USB_SS_PORT_LS_U0;
                        /* The power session apparently survived the resume.
                         * If there was an overcurrent or suspend change
                         * (i.e., remote wakeup request), have hub_wq
                         * take care of it.  Look at the port link state
                         * for USB 3.0 hubs, since they don't have a suspend
                         * change bit, and they don't set the port link change
                         * bit on device-initiated resume.
                         */
                        if (portchange || (hub_is_superspeed(hub->hdev) &&
                                                port_resumed))
                                set_bit(port1, hub->change_bits);

                } else if (udev->persist_enabled) {
#ifdef CONFIG_PM
                        udev->reset_resume = 1;
#endif
                        /* Don't set the change_bits when the device
                         * was powered off.
                         */
                        if (test_bit(port1, hub->power_bits))
                                set_bit(port1, hub->change_bits);

                } else {
                        /* The power session is gone; tell hub_wq */
                        usb_set_device_state(udev, USB_STATE_NOTATTACHED);
                        set_bit(port1, hub->change_bits);
                }
        }

        /* If no port-status-change flags were set, we don't need any
         * debouncing.  If flags were set we can try to debounce the
         * ports all at once right now, instead of letting hub_wq do them
         * one at a time later on.
         *
         * If any port-status changes do occur during this delay, hub_wq
         * will see them later and handle them normally.
         */
        if (need_debounce_delay) {
                delay = HUB_DEBOUNCE_STABLE;

                /* Don't do a long sleep inside a workqueue routine */
                if (type == HUB_INIT2) {
                        INIT_DELAYED_WORK(&hub->init_work, hub_init_func3);
                        queue_delayed_work(system_power_efficient_wq,
                                        &hub->init_work,
                                        msecs_to_jiffies(delay));
                        device_unlock(&hdev->dev);
                        return;         /* Continues at init3: below */
                } else {
                        msleep(delay);
                }
        }
 init3:
        hub->quiescing = 0;

        status = usb_submit_urb(hub->urb, GFP_NOIO);
        if (status < 0)
                dev_err(hub->intfdev, "activate --> %dn", status);
        if (hub->has_indicators && blinkenlights)
                queue_delayed_work(system_power_efficient_wq,
                                &hub->leds, LED_CYCLE_PERIOD);

        /* Scan all ports that need attention */
        kick_hub_wq(hub);
 abort:
        if (type == HUB_INIT2 || type == HUB_INIT3) {
                /* Allow autosuspend if it was suppressed */
 disconnected:
                usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
                device_unlock(&hdev->dev);
        }

        kref_put(&hub->kref, hub_release);
}

static void hub_event(struct work_struct *work)
{
        struct usb_device *hdev;
        struct usb_interface *intf;
        struct usb_hub *hub;
        struct device *hub_dev;
        u16 hubstatus;
        u16 hubchange;
        int i, ret;

        hub = container_of(work, struct usb_hub, events);  // 根hub usb_hub对象
        hdev = hub->hdev;                // 根hub   usb_device对象
        hub_dev = hub->intfdev;          // usb接口的设备基类 
        intf = to_usb_interface(hub_dev);

        dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04xn",
                        hdev->state, hdev->maxchild,
                        /* NOTE: expects max 15 ports... */
                        (u16) hub->change_bits[0],
                        (u16) hub->event_bits[0]);

        /* Lock the device, then check to see if we were
         * disconnected while waiting for the lock to succeed. */
        usb_lock_device(hdev);
        if (unlikely(hub->disconnected))
                goto out_hdev_lock;

        /* If the hub has died, clean up after it */
        if (hdev->state == USB_STATE_NOTATTACHED) {
                hub->error = -ENODEV;
                hub_quiesce(hub, HUB_DISCONNECT);
                goto out_hdev_lock;
        }

        /* Autoresume */
        ret = usb_autopm_get_interface(intf);
        if (ret) {
                dev_dbg(hub_dev, "Can't autoresume: %dn", ret);
                goto out_hdev_lock;
        }

        /* If this is an inactive hub, do nothing */
        if (hub->quiescing)
                goto out_autopm;

        if (hub->error) {
                dev_dbg(hub_dev, "resetting for error %dn", hub->error);

                ret = usb_reset_device(hdev);
                if (ret) {
                        dev_dbg(hub_dev, "error resetting hub: %dn", ret);
                        goto out_autopm;
                }

                hub->nerrors = 0;
                hub->error = 0;
        }
        /* deal with port status changes */
        for (i = 1; i <= hdev->maxchild; i++) {   // 处理变化的端口
                struct usb_port *port_dev = hub->ports[i - 1];

                if (test_bit(i, hub->event_bits)  
                                || test_bit(i, hub->change_bits)
                                || test_bit(i, hub->wakeup_bits)) {
                        /*
                         * The get_noresume and barrier ensure that if
                         * the port was in the process of resuming, we
                         * flush that work and keep the port active for
                         * the duration of the port_event().  However,
                         * if the port is runtime pm suspended
                         * (powered-off), we leave it in that state, run
                         * an abbreviated port_event(), and move on.
                         */
                        pm_runtime_get_noresume(&port_dev->dev);
                        pm_runtime_barrier(&port_dev->dev);
                        usb_lock_port(port_dev);
                        port_event(hub, i);
                        usb_unlock_port(port_dev);
                        pm_runtime_put_sync(&port_dev->dev);
                }
        }

        /* deal with hub status changes */
        if (test_and_clear_bit(0, hub->event_bits) == 0)   // 第0位为0返回true
                ;       /* do nothing */
        else if (hub_hub_status(hub, &hubstatus, &hubchange) < 0)
                dev_err(hub_dev, "get_hub_status failedn");
        else {
                if (hubchange & HUB_CHANGE_LOCAL_POWER) {
                        dev_dbg(hub_dev, "power changen");
                        clear_hub_feature(hdev, C_HUB_LOCAL_POWER);
                        if (hubstatus & HUB_STATUS_LOCAL_POWER)
                                /* FIXME: Is this always true? */
                                hub->limited_power = 1;
                        else
                                hub->limited_power = 0;
                }
                if (hubchange & HUB_CHANGE_OVERCURRENT) {
                        u16 status = 0;
                        u16 unused;

                        dev_dbg(hub_dev, "over-current changen");
                        clear_hub_feature(hdev, C_HUB_OVER_CURRENT);
                        msleep(500);    /* Cool down */
                        hub_power_on(hub, true);
                        hub_hub_status(hub, &status, &unused);
                        if (status & HUB_STATUS_OVERCURRENT)
                                dev_err(hub_dev, "over-current conditionn");
                }
        }

out_autopm:
        /* Balance the usb_autopm_get_interface() above */
        usb_autopm_put_interface_no_suspend(intf);
out_hdev_lock:
        usb_unlock_device(hdev);

        /* Balance the stuff in kick_hub_wq() and allow autosuspend */
        usb_autopm_put_interface(intf);
        kref_put(&hub->kref, hub_release);
}

static void port_event(struct usb_hub *hub, int port1)
                __must_hold(&port_dev->status_lock)
{
        int connect_change;
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_device *udev = port_dev->child;
        struct usb_device *hdev = hub->hdev;
        u16 portstatus, portchange;

        connect_change = test_bit(port1, hub->change_bits);
        clear_bit(port1, hub->event_bits);
        clear_bit(port1, hub->wakeup_bits);

        if (hub_port_status(hub, port1, &portstatus, &portchange) < 0)
                return;

        if (portchange & USB_PORT_STAT_C_CONNECTION) {
                usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_CONNECTION);
                connect_change = 1;
        }

        if (portchange & USB_PORT_STAT_C_ENABLE) {
                if (!connect_change)
                        dev_dbg(&port_dev->dev, "enable change, status %08xn",
                                        portstatus);
                usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_ENABLE);

                /*
                 * EM interference sometimes causes badly shielded USB devices
                 * to be shutdown by the hub, this hack enables them again.
                 * Works at least with mouse driver.
                 */
                if (!(portstatus & USB_PORT_STAT_ENABLE)
                    && !connect_change && udev) {
                        dev_err(&port_dev->dev, "disabled by hub (EMI?), re-enabling...n");
                        connect_change = 1;
                }
        }

        if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
                u16 status = 0, unused;
                port_dev->over_current_count++;
                port_over_current_notify(port_dev);

                dev_dbg(&port_dev->dev, "over-current change #%un",
                        port_dev->over_current_count);
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_OVER_CURRENT);
                msleep(100);    /* Cool down */
                hub_power_on(hub, true);
                hub_port_status(hub, port1, &status, &unused);
                if (status & USB_PORT_STAT_OVERCURRENT)
                        dev_err(&port_dev->dev, "over-current conditionn");
        }
 if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
                u16 status = 0, unused;
                port_dev->over_current_count++;
                port_over_current_notify(port_dev);

                dev_dbg(&port_dev->dev, "over-current change #%un",
                        port_dev->over_current_count);
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_OVER_CURRENT);
                msleep(100);    /* Cool down */
                hub_power_on(hub, true);
                hub_port_status(hub, port1, &status, &unused);
                if (status & USB_PORT_STAT_OVERCURRENT)
                        dev_err(&port_dev->dev, "over-current conditionn");
        }

        if (portchange & USB_PORT_STAT_C_RESET) {
                dev_dbg(&port_dev->dev, "reset changen");
                usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_RESET);
        }
        if ((portchange & USB_PORT_STAT_C_BH_RESET)
            && hub_is_superspeed(hdev)) {
                dev_dbg(&port_dev->dev, "warm reset changen");
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_BH_PORT_RESET);
        }
        if (portchange & USB_PORT_STAT_C_LINK_STATE) {
                dev_dbg(&port_dev->dev, "link state changen");
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_PORT_LINK_STATE);
        }
        if (portchange & USB_PORT_STAT_C_CONFIG_ERROR) {
                dev_warn(&port_dev->dev, "config errorn");
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_PORT_CONFIG_ERROR);
        }

        /* skip port actions that require the port to be powered on */
        if (!pm_runtime_active(&port_dev->dev))
                return;

        if (hub_handle_remote_wakeup(hub, port1, portstatus, portchange))
                connect_change = 1;

        /*
         * Warm reset a USB3 protocol port if it's in
         * SS.Inactive state.
         */
        if (hub_port_warm_reset_required(hub, port1, portstatus)) {
                dev_dbg(&port_dev->dev, "do warm resetn");
                if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION)
                                || udev->state == USB_STATE_NOTATTACHED) {
                        if (hub_port_reset(hub, port1, NULL,
                                        HUB_BH_RESET_TIME, true) < 0)
                                hub_port_disable(hub, port1, 1); 
                } else {
                        usb_unlock_port(port_dev);
                        usb_lock_device(udev);
                        usb_reset_device(udev);
                        usb_unlock_device(udev);
                        usb_lock_port(port_dev);
                        connect_change = 0;
                }
        }
 if (connect_change)
                hub_port_connect_change(hub, port1, portstatus, portchange);
}

/* Handle physical or logical connection change events.
 * This routine is called when:
 *      a port connection-change occurs;
 *      a port enable-change occurs (often caused by EMI);
 *      usb_reset_and_verify_device() encounters changed descriptors (as from
 *              a firmware download)
 * caller already locked the hub
 */
static void hub_port_connect_change(struct usb_hub *hub, int port1,
                                        u16 portstatus, u16 portchange)
                __must_hold(&port_dev->status_lock)
{
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_device *udev = port_dev->child;
        int status = -ENODEV;

        dev_dbg(&port_dev->dev, "status %04x, change %04x, %sn", portstatus,
                        portchange, portspeed(hub, portstatus));

        if (hub->has_indicators) {
                set_port_led(hub, port1, HUB_LED_AUTO);
                hub->indicator[port1-1] = INDICATOR_AUTO;
        }

#ifdef  CONFIG_USB_OTG
        /* during HNP, don't repeat the debounce */
        if (hub->hdev->bus->is_b_host)
                portchange &= ~(USB_PORT_STAT_C_CONNECTION |
                                USB_PORT_STAT_C_ENABLE);
#endif

        /* Try to resuscitate an existing device */
        if ((portstatus & USB_PORT_STAT_CONNECTION) && udev &&
                        udev->state != USB_STATE_NOTATTACHED) {
                if (portstatus & USB_PORT_STAT_ENABLE) {
                        status = 0;             /* Nothing to do */
#ifdef CONFIG_PM
                } else if (udev->state == USB_STATE_SUSPENDED &&
                                udev->persist_enabled) {
                        /* For a suspended device, treat this as a
                         * remote wakeup event.
                         */
                        usb_unlock_port(port_dev);
                        status = usb_remote_wakeup(udev);
                        usb_lock_port(port_dev);
#endif
                } else {
                        /* Don't resuscitate */;
                }
        }
        clear_bit(port1, hub->change_bits);

        /* successfully revalidated the connection */
        if (status == 0)
                return;

        usb_unlock_port(port_dev);
        hub_port_connect(hub, port1, portstatus, portchange);
        usb_lock_port(port_dev);
}

static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
                u16 portchange)
{
        int status = -ENODEV;
        int i;
        unsigned unit_load;
        struct usb_device *hdev = hub->hdev;
        struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_device *udev = port_dev->child;
        static int unreliable_port = -1;

        /* Disconnect any existing devices under this port */
        if (udev) {
                if (hcd->usb_phy && !hdev->parent)
                        usb_phy_notify_disconnect(hcd->usb_phy, udev->speed);
                usb_disconnect(&port_dev->child);
        }

        /* We can forget about a "removed" device when there's a physical
         * disconnect or the connect status changes.
         */
        if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
                        (portchange & USB_PORT_STAT_C_CONNECTION))
                clear_bit(port1, hub->removed_bits);

        if (portchange & (USB_PORT_STAT_C_CONNECTION |
                                USB_PORT_STAT_C_ENABLE)) {
                status = hub_port_debounce_be_stable(hub, port1);
                if (status < 0) {
                        if (status != -ENODEV &&
                                port1 != unreliable_port &&
                                printk_ratelimit())
                                dev_err(&port_dev->dev, "connect-debounce failedn");
                        portstatus &= ~USB_PORT_STAT_CONNECTION;
                        unreliable_port = port1;
                } else {
                        portstatus = status;
                }
        }

        /* Return now if debouncing failed or nothing is connected or
         * the device was "removed".
         */
        if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
                        test_bit(port1, hub->removed_bits)) {

                /*
                 * maybe switch power back on (e.g. root hub was reset)
                 * but only if the port isn't owned by someone else.
                 */
                if (hub_is_port_power_switchable(hub)
                                && !port_is_power_on(hub, portstatus)
                                && !port_dev->port_owner)
                        set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);

                if (portstatus & USB_PORT_STAT_ENABLE)
                        goto done;
                return;
        }
        if (hub_is_superspeed(hub->hdev))
                unit_load = 150;
        else
                unit_load = 100;
 status = 0;
        for (i = 0; i < SET_CONFIG_TRIES; i++) {

                /* reallocate for each attempt, since references
                 * to the previous one can escape in various ways
                 */
                udev = usb_alloc_dev(hdev, hdev->bus, port1);     // 为新的usb设备动态申请usb_device结构
                if (!udev) {
                        dev_err(&port_dev->dev,
                                        "couldn't allocate usb_devicen");
                        goto done;
                }

                usb_set_device_state(udev, USB_STATE_POWERED);  // 设置usb设备的状态标志
                udev->bus_mA = hub->mA_per_port;
                udev->level = hdev->level + 1;
                udev->wusb = hub_is_wusb(hub);

                /* Devices connected to SuperSpeed hubs are USB 3.0 or later */
                if (hub_is_superspeed(hub->hdev))
                        udev->speed = USB_SPEED_SUPER;
                else
                        udev->speed = USB_SPEED_UNKNOWN;

                choose_devnum(udev);                          // 给新的usb设备分配一个地址编号   在bus->devnum_next~128之间循环查找下一个非0值
                if (udev->devnum <= 0) {
                        status = -ENOTCONN;     /* Don't retry */
                        goto loop;
                }

                /* reset (non-USB 3.0 devices) and get descriptor */
                usb_lock_port(port_dev);
                status = hub_port_init(hub, udev, port1, i);
                usb_unlock_port(port_dev);
                if (status < 0)
                        goto loop;

                if (udev->quirks & USB_QUIRK_DELAY_INIT)
                        msleep(2000);

                /* consecutive bus-powered hubs aren't reliable; they can
                 * violate the voltage drop budget.  if the new child has
                 * a "powered" LED, users should notice we didn't enable it
                 * (without reading syslog), even without per-port LEDs
                 * on the parent.
                 */
 if (udev->descriptor.bDeviceClass == USB_CLASS_HUB
                                && udev->bus_mA <= unit_load) {
                        u16     devstat;

                        status = usb_get_std_status(udev, USB_RECIP_DEVICE, 0,
                                        &devstat);
                        if (status) {
                                dev_dbg(&udev->dev, "get status %d ?n", status);
                                goto loop_disable;
                        }
                        if ((devstat & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
                                dev_err(&udev->dev,
                                        "can't connect bus-powered hub "
                                        "to this portn");
                                if (hub->has_indicators) {
                                        hub->indicator[port1-1] =
                                                INDICATOR_AMBER_BLINK;
                                        queue_delayed_work(
                                                system_power_efficient_wq,
                                                &hub->leds, 0);
                                }
                                status = -ENOTCONN;     /* Don't retry */
                                goto loop_disable;
                        }
                }

                /* check for devices running slower than they could */
                if (le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0200
                                && udev->speed == USB_SPEED_FULL
                                && highspeed_hubs != 0)
                        check_highspeed(hub, udev, port1);

                /* Store the parent's children[] pointer.  At this point
                 * udev becomes globally accessible, although presumably
                 * no one will look at it until hdev is unlocked.
                 */
                status = 0;

                mutex_lock(&usb_port_peer_mutex);

                /* We mustn't add new devices if the parent hub has
                 * been disconnected; we would race with the
                 * recursively_mark_NOTATTACHED() routine.
                 */
                spin_lock_irq(&device_state_lock);
                if (hdev->state == USB_STATE_NOTATTACHED)
                        status = -ENOTCONN;
                else
                        port_dev->child = udev;
                spin_unlock_irq(&device_state_lock);
                mutex_unlock(&usb_port_peer_mutex);
  /* Run it through the hoops (find a driver, etc) */
                if (!status) {
                        status = usb_new_device(udev);  // 注册usb设备到内核，并匹配对应的usb设备驱动
                        if (status) {
                                mutex_lock(&usb_port_peer_mutex);
                                spin_lock_irq(&device_state_lock);
                                port_dev->child = NULL;
                                spin_unlock_irq(&device_state_lock);
                                mutex_unlock(&usb_port_peer_mutex);
                        } else {
                                if (hcd->usb_phy && !hdev->parent)
                                        usb_phy_notify_connect(hcd->usb_phy,
                                                        udev->speed);
                        }
                }

                if (status)
                        goto loop_disable;

                status = hub_power_remaining(hub);
                if (status)
                        dev_dbg(hub->intfdev, "%dmA power budget leftn", status);

                return;

loop_disable:
                hub_port_disable(hub, port1, 1);
loop:
                usb_ep0_reinit(udev);
                release_devnum(udev);
                hub_free_dev(udev);
                usb_put_dev(udev);
                if ((status == -ENOTCONN) || (status == -ENOTSUPP))
                        break;

                /* When halfway through our retry count, power-cycle the port */
                if (i == (SET_CONFIG_TRIES / 2) - 1) {
                        dev_info(&port_dev->dev, "attempt power cyclen");
                        usb_hub_set_port_power(hdev, hub, port1, false);
                        msleep(2 * hub_power_on_good_delay(hub));
                        usb_hub_set_port_power(hdev, hub, port1, true);
                        msleep(hub_power_on_good_delay(hub));
                }
        }
        if (hub->hdev->parent ||
                        !hcd->driver->port_handed_over ||
                        !(hcd->driver->port_handed_over)(hcd, port1)) {
                if (status != -ENOTCONN && status != -ENODEV)
                        dev_err(&port_dev->dev,
                                        "unable to enumerate USB devicen");
        }

done:
        hub_port_disable(hub, port1, 1);
        if (hcd->driver->relinquish_port && !hub->hdev->parent) {
                if (status != -ENOTCONN && status != -ENODEV)
                        hcd->driver->relinquish_port(hcd, port1);
        }
}

/* Reset device, (re)assign address, get device descriptor.
 * Device connection must be stable, no more debouncing needed.
 * Returns device in USB_STATE_ADDRESS, except on error.
 *
 * If this is called for an already-existing device (as part of
 * usb_reset_and_verify_device), the caller must own the device lock and
 * the port lock.  For a newly detected device that is not accessible
 * through any global pointers, it's not necessary to lock the device,
 * but it is still necessary to lock the port.
 */
static int
hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
                int retry_counter)
{
        struct usb_device       *hdev = hub->hdev;
        struct usb_hcd          *hcd = bus_to_hcd(hdev->bus);
        struct usb_port         *port_dev = hub->ports[port1 - 1];
        int                     retries, operations, retval, i;
        unsigned                delay = HUB_SHORT_RESET_TIME;
        enum usb_device_speed   oldspeed = udev->speed;
        const char              *speed;
        int                     devnum = udev->devnum;
        const char              *driver_name;

        /* root hub ports have a slightly longer reset period
         * (from USB 2.0 spec, section 7.1.7.5)
         */
        if (!hdev->parent) {
                delay = HUB_ROOT_RESET_TIME;
                if (port1 == hdev->bus->otg_port)
                        hdev->bus->b_hnp_enable = 0;
        }

        /* Some low speed devices have problems with the quick delay, so */
        /*  be a bit pessimistic with those devices. RHbug #23670 */
        if (oldspeed == USB_SPEED_LOW)
                delay = HUB_LONG_RESET_TIME;

        mutex_lock(hcd->address0_mutex);

        /* Reset the device; full speed may morph to high speed */
        /* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */
        retval = hub_port_reset(hub, port1, udev, delay, false);
        if (retval < 0)         /* error or disconnect */
                goto fail;
        /* success, speed is known */

        retval = -ENODEV;

        /* Don't allow speed changes at reset, except usb 3.0 to faster */
        if (oldspeed != USB_SPEED_UNKNOWN && oldspeed != udev->speed &&
            !(oldspeed == USB_SPEED_SUPER && udev->speed > oldspeed)) {
                dev_dbg(&udev->dev, "device reset changed speed!n");
                goto fail;
        }
        oldspeed = udev->speed;
 /* USB 2.0 section 5.5.3 talks about ep0 maxpacket ...
         * it's fixed size except for full speed devices.
         * For Wireless USB devices, ep0 max packet is always 512 (tho
         * reported as 0xff in the device descriptor). WUSB1.0[4.8.1].
         */
        switch (udev->speed) {
        case USB_SPEED_SUPER_PLUS:
        case USB_SPEED_SUPER:
        case USB_SPEED_WIRELESS:        /* fixed at 512 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(512);
                break;
        case USB_SPEED_HIGH:            /* fixed at 64 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64);
                break;
        case USB_SPEED_FULL:            /* 8, 16, 32, or 64 */
                /* to determine the ep0 maxpacket size, try to read
                 * the device descriptor to get bMaxPacketSize0 and
                 * then correct our initial guess.
                 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64);
                break;
        case USB_SPEED_LOW:             /* fixed at 8 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(8);
                break;
        default:
                goto fail;
        }

        if (udev->speed == USB_SPEED_WIRELESS)
                speed = "variable speed Wireless";
        else
                speed = usb_speed_string(udev->speed);

        /*
         * The controller driver may be NULL if the controller device
         * is the middle device between platform device and roothub.
         * This middle device may not need a device driver due to
         * all hardware control can be at platform device driver, this
         * platform device is usually a dual-role USB controller device.
         */
        if (udev->bus->controller->driver)
                driver_name = udev->bus->controller->driver->name;
        else
                driver_name = udev->bus->sysdev->driver->name;
 if (udev->speed < USB_SPEED_SUPER)
                dev_info(&udev->dev,
                                "%s %s USB device number %d using %sn",
                                (udev->config) ? "reset" : "new", speed,
                                devnum, driver_name);

        /* Set up TT records, if needed  */
        if (hdev->tt) {
                udev->tt = hdev->tt;
                udev->ttport = hdev->ttport;
        } else if (udev->speed != USB_SPEED_HIGH
                        && hdev->speed == USB_SPEED_HIGH) {
                if (!hub->tt.hub) {
                        dev_err(&udev->dev, "parent hub has no TTn");
                        retval = -EINVAL;
                        goto fail;
                }
                udev->tt = &hub->tt;
                udev->ttport = port1;
        }

        /* Why interleave GET_DESCRIPTOR and SET_ADDRESS this way?
         * Because device hardware and firmware is sometimes buggy in
         * this area, and this is how Linux has done it for ages.
         * Change it cautiously.
         *
         * NOTE:  If use_new_scheme() is true we will start by issuing
         * a 64-byte GET_DESCRIPTOR request.  This is what Windows does,
         * so it may help with some non-standards-compliant devices.
         * Otherwise we start with SET_ADDRESS and then try to read the
         * first 8 bytes of the device descriptor to get the ep0 maxpacket
         * value.
         */
        for (retries = 0; retries < GET_DESCRIPTOR_TRIES; (++retries, msleep(100))) {
                bool did_new_scheme = false;

                if (use_new_scheme(udev, retry_counter, port_dev)) {
                        struct usb_device_descriptor *buf;
                        int r = 0;

                        did_new_scheme = true;
                        retval = hub_enable_device(udev);
                        if (retval < 0) {
                                dev_err(&udev->dev,
                                        "hub failed to enable device, error %dn",
                                        retval);
                                goto fail;
                        }

#define GET_DESCRIPTOR_BUFSIZE  64
                        buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);
                        if (!buf) {
                                retval = -ENOMEM;
                                continue;
                        }

                        /* Retry on all errors; some devices are flakey.
                         * 255 is for WUSB devices, we actually need to use
                         * 512 (WUSB1.0[4.8.1]).
                         */
  for (operations = 0; operations < 3; ++operations) {
                                buf->bMaxPacketSize0 = 0;
                                r = usb_control_msg(udev, usb_rcvaddr0pipe(),
                                        USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
                                        USB_DT_DEVICE << 8, 0,
                                        buf, GET_DESCRIPTOR_BUFSIZE,
                                        initial_descriptor_timeout);
                                switch (buf->bMaxPacketSize0) {
                                case 8: case 16: case 32: case 64: case 255:
                                        if (buf->bDescriptorType ==
                                                        USB_DT_DEVICE) {
                                                r = 0;
                                                break;
                                        }
                                        /* FALL THROUGH */
                                default:
                                        if (r == 0)
                                                r = -EPROTO;
                                        break;
                                }
                                /*
                                 * Some devices time out if they are powered on
                                 * when already connected. They need a second
                                 * reset. But only on the first attempt,
                                 * lest we get into a time out/reset loop
                                 */
                                if (r == 0 || (r == -ETIMEDOUT &&
                                                retries == 0 &&
                                                udev->speed > USB_SPEED_FULL))
                                        break;
                        }
                        udev->descriptor.bMaxPacketSize0 =
                                        buf->bMaxPacketSize0;
                        kfree(buf);

                        retval = hub_port_reset(hub, port1, udev, delay, false);
                        if (retval < 0)         /* error or disconnect */
                                goto fail;
                        if (oldspeed != udev->speed) {
                                dev_dbg(&udev->dev,
                                        "device reset changed speed!n");
                                retval = -ENODEV;
                                goto fail;
                        }
                        if (r) {
                                if (r != -ENODEV)
                                        dev_err(&udev->dev, "device descriptor read/64, error %dn",
                                                        r);
                                retval = -EMSGSIZE;
                                continue;
                        }
#undef GET_DESCRIPTOR_BUFSIZE
                }

                /*
                 * If device is WUSB, we already assigned an
                 * unauthorized address in the Connect Ack sequence;
                 * authorization will assign the final address.
                 */
 if (udev->wusb == 0) {
                        for (operations = 0; operations < SET_ADDRESS_TRIES; ++operations) {
                                retval = hub_set_address(udev, devnum);
                                if (retval >= 0)
                                        break;
                                msleep(200);
                        }
                        if (retval < 0) {
                                if (retval != -ENODEV)
                                        dev_err(&udev->dev, "device not accepting address %d, error %dn",
                                                        devnum, retval);
                                goto fail;
                        }
                        if (udev->speed >= USB_SPEED_SUPER) {
                                devnum = udev->devnum;
                                dev_info(&udev->dev,
                                                "%s SuperSpeed%s%s USB device number %d using %sn",
                                                (udev->config) ? "reset" : "new",
                                         (udev->speed == USB_SPEED_SUPER_PLUS) ?
                                                        "Plus Gen 2" : " Gen 1",
                                         (udev->rx_lanes == 2 && udev->tx_lanes == 2) ?
                                                        "x2" : "",
                                         devnum, driver_name);
                        }

                        /* cope with hardware quirkiness:
                         *  - let SET_ADDRESS settle, some device hardware wants it
                         *  - read ep0 maxpacket even for high and low speed,
                         */
                        msleep(10);
                        /* use_new_scheme() checks the speed which may have
                         * changed since the initial look so we cache the result
                         * in did_new_scheme
                         */
                        if (did_new_scheme)
                                break;
                }

                retval = usb_get_device_descriptor(udev, 8);
                if (retval < 8) {
                        if (retval != -ENODEV)
                                dev_err(&udev->dev,
                                        "device descriptor read/8, error %dn",
                                        retval);
                        if (retval >= 0)
                                retval = -EMSGSIZE;
                } else {
                        u32 delay;

                        retval = 0;

                        delay = udev->parent->hub_delay;
                        udev->hub_delay = min_t(u32, delay,
                                                USB_TP_TRANSMISSION_DELAY_MAX);
                        retval = usb_set_isoch_delay(udev);
                        if (retval) {
                                dev_dbg(&udev->dev,
                                        "Failed set isoch delay, error %dn",
                                        retval);
                                retval = 0;
                        }
                        break;
                }
        }
 if (retval)
                goto fail;

        /*
         * Some superspeed devices have finished the link training process
         * and attached to a superspeed hub port, but the device descriptor
         * got from those devices show they aren't superspeed devices. Warm
         * reset the port attached by the devices can fix them.
         */
        if ((udev->speed >= USB_SPEED_SUPER) &&
                        (le16_to_cpu(udev->descriptor.bcdUSB) < 0x0300)) {
                dev_err(&udev->dev, "got a wrong device descriptor, "
                                "warm reset devicen");
                hub_port_reset(hub, port1, udev,
                                HUB_BH_RESET_TIME, true);
                retval = -EINVAL;
                goto fail;
        }

        if (udev->descriptor.bMaxPacketSize0 == 0xff ||
                        udev->speed >= USB_SPEED_SUPER)
                i = 512;
        else
                i = udev->descriptor.bMaxPacketSize0;
        if (usb_endpoint_maxp(&udev->ep0.desc) != i) {
                if (udev->speed == USB_SPEED_LOW ||
                                !(i == 8 || i == 16 || i == 32 || i == 64)) {
                        dev_err(&udev->dev, "Invalid ep0 maxpacket: %dn", i);
                        retval = -EMSGSIZE;
                        goto fail;
                }
                if (udev->speed == USB_SPEED_FULL)
                        dev_dbg(&udev->dev, "ep0 maxpacket = %dn", i);
                else
                        dev_warn(&udev->dev, "Using ep0 maxpacket: %dn", i);
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
                usb_ep0_reinit(udev);
        }

        retval = usb_get_device_descriptor(udev, USB_DT_DEVICE_SIZE);
        if (retval < (signed)sizeof(udev->descriptor)) {
                if (retval != -ENODEV)
                        dev_err(&udev->dev, "device descriptor read/all, error %dn",
                                        retval);
                if (retval >= 0)
                        retval = -ENOMSG;
                goto fail;
        }

        usb_detect_quirks(udev);

        if (udev->wusb == 0 && le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0201) {
                retval = usb_get_bos_descriptor(udev);
                if (!retval) {
                        udev->lpm_capable = usb_device_supports_lpm(udev);
                        usb_set_lpm_parameters(udev);
                }
        }

        retval = 0;
        /* notify HCD that we have a device connected and addressed */
        if (hcd->driver->update_device)
                hcd->driver->update_device(hcd, udev);
        hub_set_initial_usb2_lpm_policy(udev);
fail:
        if (retval) {
                hub_port_disable(hub, port1, 0);
                update_devnum(udev, devnum);    /* for disconnect processing */
        }
        mutex_unlock(hcd->address0_mutex);
        return retval;
}