xhci: Improve detection of device initiated wake signal.
authorMathias Nyman <mathias.nyman@linux.intel.com>
Thu, 11 Mar 2021 11:53:51 +0000 (13:53 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 11 Mar 2021 12:03:06 +0000 (13:03 +0100)
commitda1db3f5c73c3539a27be0750f8abdb536bdaf37
treea0e26e637660a65f9fb5daa0854acc25940d1fa2
parentf26554ce4eea255dc41071874339a44293235c20
xhci: Improve detection of device initiated wake signal.

A xHC USB 3 port might miss the first wake signal from a USB 3 device
if the port LFPS reveiver isn't enabled fast enough after xHC resume.

xHC host will anyway be resumed by a PME# signal, but will go back to
suspend if no port activity is seen.
The device resends the U3 LFPS wake signal after a 100ms delay, but
by then host is already suspended, starting all over from the
beginning of this issue.

USB 3 specs say U3 wake LFPS signal is sent for max 10ms, then device
needs to delay 100ms before resending the wake.

Don't suspend immediately if port activity isn't detected in resume.
Instead add a retry. If there is no port activity then delay for 120ms,
and re-check for port activity.

Cc: <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20210311115353.2137560-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/host/xhci.c