usbcore: enable USB2 LPM if port suspend fails

commit c3e751e4f4754793bb52bd5ae30e9cc027edbb12 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 95baf5dc4ab06ecd5cbfabb4deff1bf76e0ac963..ce5e1470a97dd701553306dba4df721ffa62b26c 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2419,6 +2419,10 @@ 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;