Re: [PATCH v3 2/3] drm/exynos: exynos7_drm_decon: fix call of decon_commit()

[Kaustabh Chakraborty]

On 2025-06-27 04:06, Inki Dae wrote:
> Hi,
>
> 2025년 6월 27일 (금) 오전 4:21, Kaustabh Chakraborty 
> <kauschluss@xxxxxxxxxxx>님이 작성:
> > decon_commit() has a condition guard at the beginning:
> >
> >         if (ctx->suspended)
> >                 return;
> >
> > But, when it is being called from decon_atomic_enable(), 
> > ctx->suspended
> > is still set to true, which prevents its execution. decon_commit() is
> > vital for setting up display timing values, without which the display
> > pipeline fails to function properly. Call the function after
> > ctx->suspended is set to false as a fix.
>
> Good observation. However, I think a more generic solution is needed.
>
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: 96976c3d9aff ("drm/exynos: Add DECON driver")
> > Signed-off-by: Kaustabh Chakraborty <kauschluss@xxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/exynos/exynos7_drm_decon.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/exynos/exynos7_drm_decon.c 
> > b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
> > index 
> > f91daefa9d2bc5e314c279822047e60ee0d7ca99..43bcbe2e2917df43d7c2d27a9771e892628dd682 
> > 100644
> > --- a/drivers/gpu/drm/exynos/exynos7_drm_decon.c
> > +++ b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
> > @@ -583,9 +583,9 @@ static void decon_atomic_enable(struct 
> > exynos_drm_crtc *crtc)
> >         if (test_and_clear_bit(0, &ctx->irq_flags))
> >                 decon_enable_vblank(ctx->crtc);
> >
> > -       decon_commit(ctx->crtc);
> > -
> >         ctx->suspended = false;
> > +
> > +       decon_commit(ctx->crtc);
>
> There seem to be three possible solutions:
>
> 1. Remove all code related to ctx->suspended. If the pipeline flow is
> properly managed as in the exynos5433_drm_decon.c module, checking the
> ctx->suspended state may no longer be necessary.
> 2. Remove the ctx->suspended check from decon_commit(). Since the
> runtime PM resume is already called before decon_commit() in
> decon_atomic_enable(), the DECON controller should already be enabled
> at the hardware level, and decon_commit() should work correctly.
> 3. Move the code that updates ctx->suspended from
> decon_atomic_enable() and decon_atomic_disable() to
> exynos7_decon_resume() and exynos7_decon_suspend(), respectively. The
> decon_atomic_enable() function calls pm_runtime_resume_and_get(),
> which ultimately triggers exynos7_decon_resume(). It would be more
> appropriate to set ctx->suspended = false in the
> exynos7_decon_resume() function, as this is the standard place to
> handle hardware state changes and resume actions.
> decon_atomic_enable() is responsible for requesting enablement of the
> DECON controller, but actual hardware state transitions will be
> handled within exynos7_decon_resume() and exynos7_decon_suspend().
>
>
> Unfortunately, I do not have hardware to test this patch myself. Would
> it be possible for you to try one of these approaches and verify the
> behavior?
> Option 1 would be the best solution if feasible.

Yes, it works fine indeed. Thanks!

> Thanks,
> Inki Dae
>
> >  }
> >
> >  static void decon_atomic_disable(struct exynos_drm_crtc *crtc)
> >
> > --
> > 2.49.0