| From 7e6337b694966dd7d3b9d904c830b48a4e6a80a6 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. |
| |
| From: Sarah Sharp <sarah.a.sharp@linux.intel.com> |
| |
| 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> |
| [bwh: Backported to 3.2: adjust context] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| Cc: Yang Yingliang <yangyingliang@huawei.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/usb/core/hub.c | 6 ++++++ |
| 1 file changed, 6 insertions(+) |
| |
| --- a/drivers/usb/core/hub.c |
| +++ b/drivers/usb/core/hub.c |
| @@ -4139,6 +4139,12 @@ static int usb_reset_and_verify_device(s |
| } |
| 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); |
| + |
| set_bit(port1, parent_hub->busy_bits); |
| for (i = 0; i < SET_CONFIG_TRIES; ++i) { |
| |
