usbcore: enable USB2 LPM if port suspend fails

USB2 LPM is disabled when device begin to suspend and enabled after device
is resumed. That's because USB spec does not define the transition from
U1/U2 state to U3 state.

If usb_port_suspend() fails, usb_port_resume() is never called, and USB2 LPM
is disabled in this situation. Enable USB2 LPM if port suspend fails.

This patch should be backported to kernels as old as 3.2, that contain
the commit 65580b4321eb36f16ae8b5987bfa1bb948fc5112 "xHCI: set USB2
hardware LPM".

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

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index ec6c97dadbe4dba5e3cf8a47980e23256a44bff5..c8e0704c6e5d3e0b6f13864012013f333325d0ab 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2499,6 +2499,10 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
                                NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
 
+               /* Try to enable USB2 hardware LPM again */
+               if (udev->usb2_hw_lpm_capable == 1)
+                       usb_set_usb2_hardware_lpm(udev, 1);
+
                /* System sleep transitions should never fail */
                if (!PMSG_IS_AUTO(msg))
                        status = 0;