Re: [PATCH] drm/msm/dpu: ensure device suspend happens during PM sleep

[Doug Anderson]

Hi,

On Tue, Mar 31, 2020 at 6:58 AM Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx> wrote:
>
> "The PM core always increments the runtime usage counter
> before calling the ->suspend() callback and decrements it
> after calling the ->resume() callback"
>
> DPU and DSI are managed as runtime devices. When
> suspend is triggered, PM core adds a refcount on all the
> devices and calls device suspend, since usage count is
> already incremented, runtime suspend was not getting called
> and it kept the clocks on which resulted in target not
> entering into XO shutdown.
>
> Add changes to force suspend on runtime devices during pm sleep.
>
> Changes in v1:
>  - Remove unnecessary checks in the function
>     _dpu_kms_disable_dpu (Rob Clark).
>
> Changes in v2:
>  - Avoid using suspend_late to reset the usagecount
>    as suspend_late might not be called during suspend
>    call failures (Doug).
>
> Changes in v3:
>  - Use force suspend instead of managing device usage_count
>    via runtime put and get API's to trigger callbacks (Doug).
>
> Signed-off-by: Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 2 ++
>  drivers/gpu/drm/msm/dsi/dsi.c           | 2 ++
>  drivers/gpu/drm/msm/msm_drv.c           | 4 ++++
>  3 files changed, 8 insertions(+)

This looks much saner to me.  Thanks!  I assume it still works fine
for you?  I'm still no expert on how all the pieces of DRM drivers
work together, but at least there's not a bunch of strange fiddling
with pm_runtime state and hopefully it will avoid weird corner
cases...


> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index ce19f1d..b886d9d 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -1123,6 +1123,8 @@ static int __maybe_unused dpu_runtime_resume(struct device *dev)
>
>  static const struct dev_pm_ops dpu_pm_ops = {
>         SET_RUNTIME_PM_OPS(dpu_runtime_suspend, dpu_runtime_resume, NULL)
> +       SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +                               pm_runtime_force_resume)
>  };
>
>  static const struct of_device_id dpu_dt_match[] = {
> diff --git a/drivers/gpu/drm/msm/dsi/dsi.c b/drivers/gpu/drm/msm/dsi/dsi.c
> index 55ea4bc2..62704885 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi.c
> @@ -161,6 +161,8 @@ static int dsi_dev_remove(struct platform_device *pdev)
>
>  static const struct dev_pm_ops dsi_pm_ops = {
>         SET_RUNTIME_PM_OPS(msm_dsi_runtime_suspend, msm_dsi_runtime_resume, NULL)
> +       SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +                               pm_runtime_force_resume)
>  };
>
>  static struct platform_driver dsi_driver = {
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 7d985f8..2b8c99c 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -1051,6 +1051,8 @@ static int msm_pm_suspend(struct device *dev)
>                 return ret;
>         }
>
> +       pm_runtime_force_suspend(dev);

nit: check return value of pm_runtime_force_suspend()?


> +
>         return 0;
>  }
>
> @@ -1063,6 +1065,8 @@ static int msm_pm_resume(struct device *dev)
>         if (WARN_ON(!priv->pm_state))
>                 return -ENOENT;
>
> +       pm_runtime_force_resume(dev);

nit: check return value of pm_runtime_force_resume()?


-Doug