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

[Naresh Kamboju]

Hi Rob,

On Sun, 20 Feb 2022 at 00:02, Rob Clark <robdclark@xxxxxxxxx> wrote:
>
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> Avoid going down devfreq paths on devices where devfreq is not
> initialized.
>
> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
> Reported-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>

I have tested this patch and the reported kernel crash is fixed [1].

Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

> ---
>  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),
> --
> 2.34.1


--
Linaro LKFT
https://lkft.linaro.org

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