platform/x86: amd-pmc: Fix s2idle failures on certain AMD laptops

platform/x86: amd-pmc: Fix s2idle failures on certain AMD laptops

commit 49201b90af818654c5506a0decc18e111eadcb66 upstream.

On some AMD hardware laptops, the system fails communicating with the
PMC when entering s2idle and the machine is battery powered.

Hardware description: HP Pavilion Aero Laptop 13-be0097nr
CPU: AMD Ryzen 7 5800U with Radeon Graphics
GPU: 03:00.0 VGA compatible controller [0300]: Advanced Micro Devices,
Inc. [AMD/ATI] Device [1002:1638] (rev c1)

Detailed description of the problem (and investigation) here:
https://gitlab.freedesktop.org/drm/amd/-/issues/1799

Patch is a single line: reduce the polling delay in half, from 100uSec
to 50uSec when waiting for a change in state from the PMC after a
write command operation.

After changing the delay, I did not see a single failure on this
machine (I have this fix for now more than one week and s2idle worked
every single time on battery power).

Cc: stable@vger.kernel.org
Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Signed-off-by: Fabrizio Bertocci <fabriziobertocci@gmail.com>
Link: https://lore.kernel.org/r/CADtzkx7TdfbwtaVEXUdD6YXPey52E-nZVQNs+Z41DTx7gqMqtw@mail.gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>