tree 38514abe7e4485face5fa1fb081c4a51a6f300c7
parent fc71ff7583b14347fa1cb592b698f088ecff36e3
author Andiry Xu <andiry.xu@amd.com> 1316812791 -0700
committer Greg Kroah-Hartman <gregkh@suse.de> 1317077470 -0700

xHCI: test USB2 software LPM

This patch tests USB2 software LPM for a USB2 LPM-capable device.

When a lpm-capable device is addressed, if the host also supports software
LPM, apply a test by putting the device into L1 state and resume it to see
if the device can do L1 suspend/resume successfully.

If the device fails to enter L1 or resume from L1 state, it may not
function normally and usbcore may disconnect and re-enumerate it. In this
case, store the device's Vid and Pid information, make sure the host will
not test LPM for it twice.

The test result is per device/host. Some devices claim to be lpm-capable,
but fail to enter L1 or resume. So the test is necessary.

The xHCI 1.0 errata has modified the USB2.0 LPM implementation. It redefines
the HIRD field to BESL, and adds another register Port Hardware LPM Control
(PORTHLPMC). However, this should not affect the LPM behavior on xHC which
does not implement 1.0 errata.

USB2.0 LPM errata defines a new bit BESL in the device's USB 2.0 extension
descriptor. If the device reports it uses BESL, driver should use BESL
instead of HIRD for it.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>