USB: don't use reset-resume if drivers don't support it

This patch tries to identify which devices are able to accept
reset-resume handling, by checking that there is at least one
interface driver bound and that all of the drivers have a reset_resume
method defined.  If these conditions don't hold then during resume
processing, the device is logicall disconnected.

This is only a temporary fix.  Later on we will explicitly unbind
drivers that can't handle reset-resumes.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Pavel Machek <pavel@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 8eb4da332f564c6c6daaa100a05bb27b30009d46..94789be54ca3a8c66bfd0e4b5e21c9b9112b5ab9 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -644,6 +644,48 @@ static void hub_stop(struct usb_hub *hub)
 
 #ifdef CONFIG_PM
 
+/* Try to identify which devices need USB-PERSIST handling */
+static int persistent_device(struct usb_device *udev)
+{
+       int i;
+       int retval;
+       struct usb_host_config *actconfig;
+
+       /* Explicitly not marked persistent? */
+       if (!udev->persist_enabled)
+               return 0;
+
+       /* No active config? */
+       actconfig = udev->actconfig;
+       if (!actconfig)
+               return 0;
+
+       /* FIXME! We should check whether it's open here or not! */
+
+       /*
+        * Check that all the interface drivers have a
+        * 'reset_resume' entrypoint
+        */
+       retval = 0;
+       for (i = 0; i < actconfig->desc.bNumInterfaces; i++) {
+               struct usb_interface *intf;
+               struct usb_driver *driver;
+
+               intf = actconfig->interface[i];
+               if (!intf->dev.driver)
+                       continue;
+               driver = to_usb_driver(intf->dev.driver);
+               if (!driver->reset_resume)
+                       return 0;
+               /*
+                * We have at least one driver, and that one
+                * has a reset_resume method.
+                */
+               retval = 1;
+       }
+       return retval;
+}
+
 static void hub_restart(struct usb_hub *hub, int type)
 {
        struct usb_device *hdev = hub->hdev;
@@ -689,8 +731,8 @@ static void hub_restart(struct usb_hub *hub, int type)
                 * turn off the various status changes to prevent
                 * khubd from disconnecting it later.
                 */
-               if (udev->persist_enabled && status == 0 &&
-                               !(portstatus & USB_PORT_STAT_ENABLE)) {
+               if (status == 0 && !(portstatus & USB_PORT_STAT_ENABLE) &&
+                               persistent_device(udev)) {
                        if (portchange & USB_PORT_STAT_C_ENABLE)
                                clear_port_feature(hub->hdev, port1,
                                                USB_PORT_FEAT_C_ENABLE);