linux-kernel - Re: [PATCH] drm: msm: a6xx: fix gpu failure after system resume

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Message-ID: <20200714171036.GS3191083@google.com>
Date:   Tue, 14 Jul 2020 10:10:36 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Akhil P Oommen <akhilpo@...eaurora.org>
Cc:     freedreno@...ts.freedesktop.org, dri-devel@...edesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        jcrouse@...eaurora.org, devicetree@...r.kernel.org,
        jonathan@...ek.ca, robdclark@...il.com, rnayak@...eaurora.org
Subject: Re: [PATCH] drm: msm: a6xx: fix gpu failure after system resume

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@...eaurora.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@...omium.org>
Tested-by: Matthias Kaehlcke <mka@...omium.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.