[PATCH] drm: msm: a6xx: fix gpu failure after system resume

[Matthias Kaehlcke]

On Tue, Jul 14, 2020 at 06:55:30PM +0530, Akhil P Oommen wrote:
> On targets where GMU is available, GMU takes over the ownership of GX GDSC
> during its initialization. So, take a refcount on the GX PD on behalf of
> GMU before we initialize it. This makes sure that nobody can collapse the
> GX GDSC once GMU owns the GX GDSC. This patch fixes some weird failures
> during GPU wake up during system resume.
> 
> Signed-off-by: Akhil P Oommen <akhilpo at codeaurora.org>

I went through a few dozen suspend/resume cycles on SC7180 and didn't run
into the kernel panic that typically occurs after a few iterations without
this patch.

Reported-by: Matthias Kaehlcke <mka at chromium.org>
Tested-by: Matthias Kaehlcke <mka at chromium.org>

On which tree is this patch based on? I had to apply it manually because
'git am' is unhappy when I try to apply it:

  error: sha1 information is lacking or useless (drivers/gpu/drm/msm/adreno/a6xx_gmu.c).
  error: could not build fake ancestor

Both upstream and drm-msm are in my remotes and synced, so I suspect it's
some private tree. Please make sure to base patches on the corresponding
maintainer tree or upstream, whichs makes life easier for maintainers,
testers and reviewers.