[PATCH] drm/msm/gpu: Fix crash on devices without devfreq support

[Naresh Kamboju]

Hi Rob and Linus,

On Mon, 7 Mar 2022 at 14:07, Naresh Kamboju <naresh.kamboju at linaro.org> wrote:
>
> Hi Rob,
>
> On Sun, 20 Feb 2022 at 00:02, Rob Clark <robdclark at gmail.com> wrote:
> >
> > From: Rob Clark <robdclark at chromium.org>
> >
> > Avoid going down devfreq paths on devices where devfreq is not
> > initialized.
> >
> > Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>
> > Reported-by: Anders Roxell <anders.roxell at linaro.org>
> > Signed-off-by: Rob Clark <robdclark at chromium.org>
>
> I have tested this patch and the reported kernel crash is fixed [1].
>
> Tested-by: Linux Kernel Functional Testing <lkft at linaro.org>
>
> > ---
> >  drivers/gpu/drm/msm/msm_gpu_devfreq.c | 31 +++++++++++++++++++++------
> >  1 file changed, 25 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> > index 9bf319be11f6..26a3669a97b3 100644
> > --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> > +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> > @@ -83,12 +83,17 @@ static struct devfreq_dev_profile msm_devfreq_profile = {
> >  static void msm_devfreq_boost_work(struct kthread_work *work);
> >  static void msm_devfreq_idle_work(struct kthread_work *work);
> >
> > +static bool has_devfreq(struct msm_gpu *gpu)
> > +{
> > +       return !!gpu->funcs->gpu_busy;
> > +}
> > +
> >  void msm_devfreq_init(struct msm_gpu *gpu)
> >  {
> >         struct msm_gpu_devfreq *df = &gpu->devfreq;
> >
> >         /* We need target support to do devfreq */
> > -       if (!gpu->funcs->gpu_busy)
> > +       if (!has_devfreq(gpu))
> >                 return;
> >
> >         dev_pm_qos_add_request(&gpu->pdev->dev, &df->idle_freq,
> > @@ -149,6 +154,9 @@ void msm_devfreq_cleanup(struct msm_gpu *gpu)
> >  {
> >         struct msm_gpu_devfreq *df = &gpu->devfreq;
> >
> > +       if (!has_devfreq(gpu))
> > +               return;
> > +
> >         devfreq_cooling_unregister(gpu->cooling);
> >         dev_pm_qos_remove_request(&df->boost_freq);
> >         dev_pm_qos_remove_request(&df->idle_freq);
> > @@ -156,16 +164,24 @@ void msm_devfreq_cleanup(struct msm_gpu *gpu)
> >
> >  void msm_devfreq_resume(struct msm_gpu *gpu)
> >  {
> > -       gpu->devfreq.busy_cycles = 0;
> > -       gpu->devfreq.time = ktime_get();
> > +       struct msm_gpu_devfreq *df = &gpu->devfreq;
> >
> > -       devfreq_resume_device(gpu->devfreq.devfreq);
> > +       if (!has_devfreq(gpu))
> > +               return;
> > +
> > +       df->busy_cycles = 0;
> > +       df->time = ktime_get();
> > +
> > +       devfreq_resume_device(df->devfreq);
> >  }
> >
> >  void msm_devfreq_suspend(struct msm_gpu *gpu)
> >  {
> >         struct msm_gpu_devfreq *df = &gpu->devfreq;
> >
> > +       if (!has_devfreq(gpu))
> > +               return;
> > +
> >         devfreq_suspend_device(df->devfreq);
> >
> >         cancel_idle_work(df);
> > @@ -185,6 +201,9 @@ void msm_devfreq_boost(struct msm_gpu *gpu, unsigned factor)
> >         struct msm_gpu_devfreq *df = &gpu->devfreq;
> >         uint64_t freq;
> >
> > +       if (!has_devfreq(gpu))
> > +               return;
> > +
> >         freq = get_freq(gpu);
> >         freq *= factor;
> >
> > @@ -207,7 +226,7 @@ void msm_devfreq_active(struct msm_gpu *gpu)
> >         struct devfreq_dev_status status;
> >         unsigned int idle_time;
> >
> > -       if (!df->devfreq)
> > +       if (!has_devfreq(gpu))
> >                 return;
> >
> >         /*
> > @@ -253,7 +272,7 @@ void msm_devfreq_idle(struct msm_gpu *gpu)
> >  {
> >         struct msm_gpu_devfreq *df = &gpu->devfreq;
> >
> > -       if (!df->devfreq)
> > +       if (!has_devfreq(gpu))
> >                 return;
> >
> >         msm_hrtimer_queue_work(&df->idle_work, ms_to_ktime(1),

FYI,
This patch is missing on Linux 5.17-rc8 [1].
kernel crash log on arm64 db410c device [2] and details [3].

metadata:
  git_describe: v5.17-rc8
  git_ref: master
  git_repo: https://gitlab.com/Linaro/lkft/mirrors/torvalds/linux-mainline
  git_sha: 09688c0166e76ce2fb85e86b9d99be8b0084cdf9
  kernel-config: https://builds.tuxbuild.com/26LbbVLHqxjh5w5ZtjBMjGmh92P/config
  build: https://builds.tuxbuild.com/26LbbVLHqxjh5w5ZtjBMjGmh92P

- Naresh
[1] https://lore.kernel.org/dri-devel/20220219183310.557435-1-robdclark@gmail.com/
[2]  https://lkft.validation.linaro.org/scheduler/job/4714905#L2795
[3] https://qa-reports.linaro.org/lkft/linux-mainline-master/build/v5.17-rc8/testrun/8446224/suite/linux-log-parser/test/check-kernel-oops-4714905/details/

>
> --
> Linaro LKFT
> https://lkft.linaro.org
>
> [1] https://lkft.validation.linaro.org/scheduler/job/4664600#L1894