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

[kalyan_t@xxxxxxxxxxxxxx]

On 2020-03-31 21:30, Doug Anderson wrote:
> 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...
--- Yes, verified the change on trogdor device, and display can suspend 
with the change.
> > 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