[PATCH] drm/panfrost: Make devfreq truly optional

[Rob Herring]

On Mon, May 13, 2019 at 12:56 PM Ezequiel Garcia <ezequiel at collabora.com> wrote:
>
> Currently, there is some logic to make devfreq optional,
> but it fails to cover some cases such as !CONFIG_PM_DEVFREQ.

Fails how? compiling? runtime? Or just builds extra code?

> Moreover, depending on return codes is not resilient to change,
> so let's take a different approach, introducing proper
> stubs and only conditionally compiling the devfreq support.

The downside here is another build time configuration to test. Isn't
devfreq essentially going to be required to run the GPU at higher
frequencies and to not melt it?

>
> Signed-off-by: Ezequiel Garcia <ezequiel at collabora.com>
> ---
>  drivers/gpu/drm/panfrost/Makefile           |  3 ++-
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 13 ++-----------
>  drivers/gpu/drm/panfrost/panfrost_devfreq.h | 19 +++++++++++++++++--
>  3 files changed, 21 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/panfrost/Makefile b/drivers/gpu/drm/panfrost/Makefile
> index 6de72d13c58f..8b690672f9d9 100644
> --- a/drivers/gpu/drm/panfrost/Makefile
> +++ b/drivers/gpu/drm/panfrost/Makefile
> @@ -3,10 +3,11 @@
>  panfrost-y := \
>         panfrost_drv.o \
>         panfrost_device.o \
> -       panfrost_devfreq.o \
>         panfrost_gem.o \
>         panfrost_gpu.o \
>         panfrost_job.o \
>         panfrost_mmu.o
>
> +panfrost-$(CONFIG_PM_DEVFREQ) += panfrost_devfreq.o
> +
>  obj-$(CONFIG_DRM_PANFROST) += panfrost.o
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> index 238bd1d89d43..29fcffdf2d57 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> @@ -140,8 +140,8 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
>                 return 0;
>
>         ret = dev_pm_opp_of_add_table(&pfdev->pdev->dev);
> -       if (ret == -ENODEV) /* Optional, continue without devfreq */
> -               return 0;
> +       if (ret)
> +               return ret;
>
>         panfrost_devfreq_reset(pfdev);
>
> @@ -170,9 +170,6 @@ void panfrost_devfreq_resume(struct panfrost_device *pfdev)
>  {
>         int i;
>
> -       if (!pfdev->devfreq.devfreq)
> -               return;
> -
>         panfrost_devfreq_reset(pfdev);
>         for (i = 0; i < NUM_JOB_SLOTS; i++)
>                 pfdev->devfreq.slot[i].busy = false;
> @@ -182,9 +179,6 @@ void panfrost_devfreq_resume(struct panfrost_device *pfdev)
>
>  void panfrost_devfreq_suspend(struct panfrost_device *pfdev)
>  {
> -       if (!pfdev->devfreq.devfreq)
> -               return;
> -
>         devfreq_suspend_device(pfdev->devfreq.devfreq);
>  }
>
> @@ -194,9 +188,6 @@ static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, i
>         ktime_t now;
>         ktime_t last;
>
> -       if (!pfdev->devfreq.devfreq)
> -               return;
> -
>         now = ktime_get();
>         last = pfdev->devfreq.slot[slot].time_last_update;
>
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.h b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> index eb999531ed90..76b56a8de6e3 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> @@ -4,11 +4,26 @@
>  #ifndef __PANFROST_DEVFREQ_H__
>  #define __PANFROST_DEVFREQ_H__
>
> +#if defined(CONFIG_PM_DEVFREQ)
>  int panfrost_devfreq_init(struct panfrost_device *pfdev);
> -
>  void panfrost_devfreq_resume(struct panfrost_device *pfdev);
>  void panfrost_devfreq_suspend(struct panfrost_device *pfdev);
> -
>  void panfrost_devfreq_record_transition(struct panfrost_device *pfdev, int slot);
> +#else
> +static inline int panfrost_devfreq_init(struct panfrost_device *pfdev)
> +{
> +       return 0;
> +}
> +
> +static inline void panfrost_devfreq_resume(struct panfrost_device *pfdev)
> +{}
> +
> +static inline void panfrost_devfreq_suspend(struct panfrost_device *pfdev)
> +{}
> +
> +static inline void
> +panfrost_devfreq_record_transition(struct panfrost_device *pfdev, int slot)
> +{}
> +#endif
>
>  #endif /* __PANFROST_DEVFREQ_H__ */
> --
> 2.20.1
>