USB: Disable LPM while the device is unconfigured.

The USB 3.0 Set/Clear Feature U1/U2 Enable cannot be sent to a device in
the Default or Addressed state.  It can only be sent to a configured
device.  Change the USB core to initialize the LPM disable count to 1
(disabled), which reflects this limitation.

Change usb_set_configuration() to ensure that if the device is
unconfigured on entry, usb_lpm_disable() is not called.  This avoids
sending the Clear Feature U1/U2 when the device is in the Addressed
state.  When usb_set_configuration() exits with a successfully installed
configuration, usb_lpm_enable() will be called.

Once the new configuration is installed, make sure
usb_set_configuration() only calls usb_enable_lpm() if the device moved
to the Configured state.  If we have unconfigured the device by sending
it a Set Configuration for config 0, don't enable LPM.

This commit should be backported to kernels as old as 3.5, that contain
the commit 8306095 "USB: Disable USB
3.0 LPM in critical sections."

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

drivers/usb/core/message.c

@@ -1792,14 +1792,15 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
 	 * installed, so that the xHCI driver can recalculate the U1/U2
 	 * timeouts.
 	 */
-	if (usb_disable_lpm(dev)) {
+	if (dev->actconfig && usb_disable_lpm(dev)) {
 		dev_err(&dev->dev, "%s Failed to disable LPM\n.", __func__);
 		mutex_unlock(hcd->bandwidth_mutex);
 		return -ENOMEM;
 	}
 	ret = usb_hcd_alloc_bandwidth(dev, cp, NULL, NULL);
 	if (ret < 0) {
-		usb_enable_lpm(dev);
+		if (dev->actconfig)
+			usb_enable_lpm(dev);
 		mutex_unlock(hcd->bandwidth_mutex);
 		usb_autosuspend_device(dev);
 		goto free_interfaces;
@@ -1819,7 +1820,7 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
 	if (!cp) {
 		usb_set_device_state(dev, USB_STATE_ADDRESS);
 		usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
-		usb_enable_lpm(dev);
+		/* Leave LPM disabled while the device is unconfigured. */
 		mutex_unlock(hcd->bandwidth_mutex);
 		usb_autosuspend_device(dev);
 		goto free_interfaces;

drivers/usb/core/usb.c

@@ -396,6 +396,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 	dev->dev.dma_mask = bus->controller->dma_mask;
 	set_dev_node(&dev->dev, dev_to_node(bus->controller));
 	dev->state = USB_STATE_ATTACHED;
+	dev->lpm_disable_count = 1;
 	atomic_set(&dev->urbnum, 0);
 
 	INIT_LIST_HEAD(&dev->ep0.urb_list);