linux-kernel - Re: [PATCH v1 3/3] msm: skip the atomic commit of self refresh while PSR running

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Message-ID: <CAA8EJppc3LDQy2RgVZbWki4Y-_FOTK67Y8RfK5Bm9gqdfqMjqQ@mail.gmail.com>
Date:   Fri, 31 Mar 2023 17:58:12 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Vinod Polimera <quic_vpolimer@...cinc.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, robdclark@...il.com,
        dianders@...omium.org, swboyd@...omium.org,
        quic_kalyant@...cinc.com, quic_khsieh@...cinc.com,
        quic_vproddut@...cinc.com, quic_bjorande@...cinc.com,
        quic_abhinavk@...cinc.com, quic_sbillaka@...cinc.com
Subject: Re: [PATCH v1 3/3] msm: skip the atomic commit of self refresh while
 PSR running

On Fri, 31 Mar 2023 at 16:59, Vinod Polimera <quic_vpolimer@...cinc.com> wrote:
>
> In certain CPU stress conditions, there can be a delay in scheduling commit
> work and it was observed that PSR commit from a different work queue was
> scheduled. Avoid these commits as display is already in PSR mode.
>
> Signed-off-by: Vinod Polimera <quic_vpolimer@...cinc.com>
> ---
>  drivers/gpu/drm/msm/msm_atomic.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
> index 645fe53..f8141bb 100644
> --- a/drivers/gpu/drm/msm/msm_atomic.c
> +++ b/drivers/gpu/drm/msm/msm_atomic.c
> @@ -192,6 +192,9 @@ int msm_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
>                         new_crtc_state->mode_changed = true;
>                         state->allow_modeset = true;
>                 }
> +
> +               if (old_crtc_state->self_refresh_active && new_crtc_state->self_refresh_active)
> +                       return -EINVAL;

EINVAL here means that atomic_check will fail if both old and new
states are in SR mode. For example, there might be a mode set for
another CRTC (while keeping this one in SR mode). I don't think this
is correct. We should skip/shortcut the commit, that's true. But I
doubt that returning an error here is a proper way to do this. Please
correct me if I'm wrong.

>         }
>
>         return drm_atomic_helper_check(dev, state);
> --
> 2.7.4
>


-- 
With best wishes
Dmitry