USB: re-enable interface after driver unbinds

This patch (as1197) fixes an error introduced recently.  Since a
significant number of devices can't handle Set-Interface requests, we
no longer call usb_set_interface() when a driver unbinds from an
interface, provided the interface is already in altsetting 0.  However
the interface still does get disabled, and the call to
usb_set_interface() was the only thing re-enabling it.  Since the
interface doesn't get re-enabled, further attempts to use it fail.

So the patch adds a call to usb_enable_interface() when a driver
unbinds and the interface is in altsetting 0.  For this to work
right, the interface's endpoints have to be re-enabled but their
toggles have to be left alone.  Therefore an additional argument is
added to usb_enable_endpoint() and usb_enable_interface(), a flag
indicating whether or not the endpoint toggles should be reset.

This is a forward-ported version of a patch which fixes Bugzilla
#12301.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: David Roka <roka@dawid.hu>
Reported-by: Erik Ekman <erik@kryo.se>
Tested-by: Erik Ekman <erik@kryo.se>
Tested-by: Alon Bar-Lev <alon.barlev@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

5 files changed, 26 insertions, 16 deletions

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 41c06025506e..98760553bc95 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -295,9 +295,12 @@ static int usb_unbind_interface(struct device *dev)
          * altsetting means creating new endpoint device entries).
          * When either of these happens, defer the Set-Interface.
          */
-        if (intf->cur_altsetting->desc.bAlternateSetting == 0)
-                ;       /* Already in altsetting 0 so skip Set-Interface */
-        else if (!error && intf->dev.power.status == DPM_ON)
+        if (intf->cur_altsetting->desc.bAlternateSetting == 0) {
+                /* Already in altsetting 0 so skip Set-Interface.
+                 * Just re-enable it without affecting the endpoint toggles.
+                 */
+                usb_enable_interface(udev, intf, false);
+        } else if (!error && intf->dev.power.status == DPM_ON)
                 usb_set_interface(udev, intf->altsetting[0].
                                 desc.bInterfaceNumber, 0);
         else
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 756b8d9993fc..d5d0e40b1e2d 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2384,7 +2384,7 @@ void usb_ep0_reinit(struct usb_device *udev)
 {
         usb_disable_endpoint(udev, 0 + USB_DIR_IN);
         usb_disable_endpoint(udev, 0 + USB_DIR_OUT);
-        usb_enable_endpoint(udev, &udev->ep0);
+        usb_enable_endpoint(udev, &udev->ep0, true);
 }
 EXPORT_SYMBOL_GPL(usb_ep0_reinit);
 
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 5589686981f1..de51667dd64d 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1143,22 +1143,26 @@ void usb_disable_device(struct usb_device *dev, int skip_ep0)
  * usb_enable_endpoint - Enable an endpoint for USB communications
  * @dev: the device whose interface is being enabled
  * @ep: the endpoint
+ * @reset_toggle: flag to set the endpoint's toggle back to 0
  *
- * Resets the endpoint toggle, and sets dev->ep_{in,out} pointers.
+ * Resets the endpoint toggle if asked, and sets dev->ep_{in,out} pointers.
  * For control endpoints, both the input and output sides are handled.
  */
-void usb_enable_endpoint(struct usb_device *dev, struct usb_host_endpoint *ep)
+void usb_enable_endpoint(struct usb_device *dev, struct usb_host_endpoint *ep,
+                bool reset_toggle)
 {
         int epnum = usb_endpoint_num(&ep->desc);
         int is_out = usb_endpoint_dir_out(&ep->desc);
         int is_control = usb_endpoint_xfer_control(&ep->desc);
 
         if (is_out || is_control) {
-                usb_settoggle(dev, epnum, 1, 0);
+                if (reset_toggle)
+                        usb_settoggle(dev, epnum, 1, 0);
                 dev->ep_out[epnum] = ep;
         }
         if (!is_out || is_control) {
-                usb_settoggle(dev, epnum, 0, 0);
+                if (reset_toggle)
+                        usb_settoggle(dev, epnum, 0, 0);
                 dev->ep_in[epnum] = ep;
         }
         ep->enabled = 1;
@@ -1168,17 +1172,18 @@ void usb_enable_endpoint(struct usb_device *dev, struct usb_host_endpoint *ep)
  * usb_enable_interface - Enable all the endpoints for an interface
  * @dev: the device whose interface is being enabled
  * @intf: pointer to the interface descriptor
+ * @reset_toggles: flag to set the endpoints' toggles back to 0
  *
  * Enables all the endpoints for the interface's current altsetting.
  */
-static void usb_enable_interface(struct usb_device *dev,
-                                 struct usb_interface *intf)
+void usb_enable_interface(struct usb_device *dev,
+                struct usb_interface *intf, bool reset_toggles)
 {
         struct usb_host_interface *alt = intf->cur_altsetting;
         int i;
 
         for (i = 0; i < alt->desc.bNumEndpoints; ++i)
-                usb_enable_endpoint(dev, &alt->endpoint[i]);
+                usb_enable_endpoint(dev, &alt->endpoint[i], reset_toggles);
 }
 
 /**
@@ -1303,7 +1308,7 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
          * during the SETUP stage - hence EP0 toggles are "don't care" here.
          * (Likewise, EP0 never "halts" on well designed devices.)
          */
-        usb_enable_interface(dev, iface);
+        usb_enable_interface(dev, iface, true);
         if (device_is_registered(&iface->dev)) {
                 usb_create_sysfs_intf_files(iface);
                 create_intf_ep_devs(iface);
@@ -1382,7 +1387,7 @@ int usb_reset_configuration(struct usb_device *dev)
                         usb_remove_sysfs_intf_files(intf);
                 }
                 intf->cur_altsetting = alt;
-                usb_enable_interface(dev, intf);
+                usb_enable_interface(dev, intf, true);
                 if (device_is_registered(&intf->dev)) {
                         usb_create_sysfs_intf_files(intf);
                         create_intf_ep_devs(intf);
@@ -1685,7 +1690,7 @@ free_interfaces:
                         alt = &intf->altsetting[0];
 
                 intf->cur_altsetting = alt;
-                usb_enable_interface(dev, intf);
+                usb_enable_interface(dev, intf, true);
                 intf->dev.parent = &dev->dev;
                 intf->dev.driver = NULL;
                 intf->dev.bus = &usb_bus_type;
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index c0821564a3fe..dcfc072630c1 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -362,7 +362,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
         dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
         dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
         /* ep0 maxpacket comes later, from device descriptor */
-        usb_enable_endpoint(dev, &dev->ep0);
+        usb_enable_endpoint(dev, &dev->ep0, true);
         dev->can_submit = 1;
 
         /* Save readable and stable topology id, distinguishing devices
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index 381eae90c3b7..386177867a8a 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -12,7 +12,9 @@ extern int usb_create_ep_devs(struct device *parent,
 extern void usb_remove_ep_devs(struct usb_host_endpoint *endpoint);
 
 extern void usb_enable_endpoint(struct usb_device *dev,
-                struct usb_host_endpoint *ep);
+                struct usb_host_endpoint *ep, bool reset_toggle);
+extern void usb_enable_interface(struct usb_device *dev,
+                struct usb_interface *intf, bool reset_toggles);
 extern void usb_disable_endpoint(struct usb_device *dev, unsigned int epaddr);
 extern void usb_disable_interface(struct usb_device *dev,
                 struct usb_interface *intf);