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 8306095fd2c1100e8244c09bf560f97aca5a311d "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

2 files changed, 5 insertions, 3 deletions

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 8b9d669e3784..37239048be14 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1792,14 +1792,15 @@ free_interfaces:
          * 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 @@ free_interfaces:
         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;
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 25d0c61c3f8a..cd8fb44a3e16 100644
--- a/drivers/usb/core/usb.c
+++ b/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);