USB hub: simplify remote-wakeup handling

This patch (as817) simplifies the remote-wakeup processing in the hub
driver.  Now instead of using a specialized code path, it relies on
the standard USB resume routines.  The hub_port_resume() function does
an initial get_port_status() to see whether the port has already
resumed itself (as it does when a remote-wakeup request is sent).
This will slow down handling of other resume events slightly, but not
enough to matter.

The patch also changes the hub_port_status() routine, making it return
an error if a short reply is received.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 20 insertions, 23 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 55812a5ac661..46df5e60764b 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1409,10 +1409,12 @@ static int hub_port_status(struct usb_hub *hub, int port1,
         int ret;
 
         ret = get_port_status(hub->hdev, port1, &hub->status->port);
-        if (ret < 0)
+        if (ret < 4) {
                 dev_err (hub->intfdev,
                         "%s failed (err = %d)\n", __FUNCTION__, ret);
-        else {
+                if (ret >= 0)
+                        ret = -EIO;
+        } else {
                 *status = le16_to_cpu(hub->status->port.wPortStatus);
                 *change = le16_to_cpu(hub->status->port.wPortChange); 
                 ret = 0;
@@ -1760,6 +1762,12 @@ static int
 hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
 {
         int     status;
+        u16     portchange, portstatus;
+
+        /* Skip the initial Clear-Suspend step for a remote wakeup */
+        status = hub_port_status(hub, port1, &portstatus, &portchange);
+        if (status == 0 && !(portstatus & USB_PORT_STAT_SUSPEND))
+                goto SuspendCleared;
 
         // dev_dbg(hub->intfdev, "resume port %d\n", port1);
 
@@ -1773,9 +1781,6 @@ hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
                         "can't resume port %d, status %d\n",
                         port1, status);
         } else {
-                u16             devstatus;
-                u16             portchange;
-
                 /* drive resume for at least 20 msec */
                 if (udev)
                         dev_dbg(&udev->dev, "usb %sresume\n",
@@ -1790,16 +1795,15 @@ hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
                  * stop resume signaling.  Then finish the resume
                  * sequence.
                  */
-                devstatus = portchange = 0;
-                status = hub_port_status(hub, port1,
-                                &devstatus, &portchange);
+                status = hub_port_status(hub, port1, &portstatus, &portchange);
+SuspendCleared:
                 if (status < 0
-                                || (devstatus & LIVE_FLAGS) != LIVE_FLAGS
-                                || (devstatus & USB_PORT_STAT_SUSPEND) != 0
+                                || (portstatus & LIVE_FLAGS) != LIVE_FLAGS
+                                || (portstatus & USB_PORT_STAT_SUSPEND) != 0
                                 ) {
                         dev_dbg(hub->intfdev,
                                 "port %d status %04x.%04x after resume, %d\n",
-                                port1, portchange, devstatus, status);
+                                port1, portchange, portstatus, status);
                         if (status >= 0)
                                 status = -ENODEV;
                 } else {
@@ -1860,23 +1864,16 @@ static int remote_wakeup(struct usb_device *udev)
 {
         int     status = 0;
 
-        /* All this just to avoid sending a port-resume message
-         * to the parent hub! */
-
         usb_lock_device(udev);
-        usb_pm_lock(udev);
         if (udev->state == USB_STATE_SUSPENDED) {
                 dev_dbg(&udev->dev, "usb %sresume\n", "wakeup-");
-                /* TRSMRCY = 10 msec */
-                msleep(10);
-                status = finish_port_resume(udev);
+                status = usb_autoresume_device(udev, 1);
+
+                /* Give the interface drivers a chance to do something,
+                 * then autosuspend the device again. */
                 if (status == 0)
-                        udev->dev.power.power_state.event = PM_EVENT_ON;
+                        usb_autosuspend_device(udev, 1);
         }
-        usb_pm_unlock(udev);
-
-        if (status == 0)
-                usb_autoresume_device(udev, 0);
         usb_unlock_device(udev);
         return status;
 }