@@ -4824,6 +4824,12 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
}
parent_hub = hdev_to_hub(parent_hdev);
+ /* Disable USB2 hardware LPM.
+ * It will be re-enabled by the enumeration process.
+ */
+ if (udev->usb2_hw_lpm_enabled == 1)
+ usb_set_usb2_hardware_lpm(udev, 0);
+
/* Disable LPM while we reset the device and reinstall the alt settings.
* Device-initiated LPM settings, and system exit latency settings are
* cleared when the device is reset, so we have to set them up again.
This is a note to let you know that I have just added a patch titled usb: Disable USB 2.0 Link PM before device reset. to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From ff4af1548ff1d4141157a5a13fb6da2cbe20ec21 Mon Sep 17 00:00:00 2001 From: Sarah Sharp <sarah.a.sharp@linux.intel.com> Date: Mon, 30 Sep 2013 17:26:29 +0300 Subject: usb: Disable USB 2.0 Link PM before device reset. commit dcc01c0864823f91c3bf3ffca6613e2351702b87 upstream. Before the USB core resets a device, we need to disable the L1 timeout for the roothub, if USB 2.0 Link PM is enabled. Otherwise the port may transition into L1 in between descriptor fetches, before we know if the USB device descriptors changed. LPM will be re-enabled after the full device descriptors are fetched, and we can confirm the device still supports USB 2.0 LPM after the reset. We don't need to wait for the USB device to exit L1 before resetting the device, since the xHCI roothub port diagrams show a transition to the Reset state from any of the Ux states (see Figure 34 in the 2012-08-14 xHCI specification update). This patch should be backported to kernels as old as 3.2, that contain the commit 65580b4321eb36f16ae8b5987bfa1bb948fc5112 "xHCI: set USB2 hardware LPM". That was the first commit to enable USB 2.0 hardware-driven Link Power Management. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> [ luis: backported to 3.5: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/usb/core/hub.c | 6 ++++++ 1 file changed, 6 insertions(+) -- 1.8.3.2