Re: [PATCH] drm/msm: Disable frequency clamping on a630

[Rob Clark <robdclark@gmail.com>]

On Tue, Sep 7, 2021 at 1:25 AM Amit Pundir <amit.pundir@linaro.org> wrote:
>
> On Tue, 7 Sept 2021 at 07:11, Rob Clark <robdclark@gmail.com> wrote:
> >
> > One thing I thought of, which would be worth ruling out, is whether
> > this issue only occurs with freq changes immediately after resuming
> > the GPU, vs freq changes in general.  Could you try the below patch.
> > And if it "fixes" the issue, then try reducing the delay until you
> > start seeing GPU hangs again.
>
> It doesn't fix the crash and I can still reproduce it
> https://pastebin.com/raw/bxK4mAhB

Ok, thanks for confirming.  That implies the limitation is about
changing freq in general, rather than immediately after resume.. the
latter could be a new scenario after 9bc95570175a.  But this confirms
that this is an issue that has been there all along.

I'm still not quite sure what the correct fix is

BR,
-R

>
> >
> > ----------
> > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > index 40c9fef457a4..278b85207ea3 100644
> > --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > @@ -1513,6 +1513,8 @@ static int a6xx_pm_resume(struct msm_gpu *gpu)
> >   if (ret)
> >   return ret;
> >
> > + msleep(5);
> > +
> >   msm_devfreq_resume(gpu);
> >
> >   a6xx_llc_activate(a6xx_gpu);
> > ----------
> >
> > BR,
> > -R