Re: [PATCH v8 12/13] drm/atomic-helper: Re-order bridge chain pre-enable and post-disable

Dmitry Baryshkov
2025-01-26T21:55:54Z

On Mon, Jan 27, 2025 at 12:45:50AM +0530, Aradhya Bhatia wrote:
> Move the bridge pre_enable call before crtc enable, and the bridge
> post_disable call after the crtc disable.
>
> The sequence of enable after this patch will look like:
>
> bridge[n]_pre_enable
> ...
> bridge[1]_pre_enable
>
> crtc_enable
> encoder_enable
>
> bridge[1]_enable
> ...
> bridge[n]_enable
>
> And, the disable sequence for the display pipeline will look like:
>
> bridge[n]_disable
> ...
> bridge[1]_disable
>
> encoder_disable
> crtc_disable
>
> bridge[1]_post_disable
> ...
> bridge[n]_post_disable
>
> The definition of bridge pre_enable hook says that,
> "The display pipe (i.e. clocks and timing signals) feeding this bridge
> will not yet be running when this callback is called".
>
> Since CRTC is also a source feeding the bridge, it should not be enabled
> before the bridges in the pipeline are pre_enabled. Fix that by
> re-ordering the sequence of bridge pre_enable and bridge post_disable.
>
> Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
> Signed-off-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
> ---
> drivers/gpu/drm/drm_atomic_helper.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>

I don't feel confident enough to say that I understand all the
consequences of this change. On the other hand it sounds pretty logical,
isolated and can be tested separately.

Acked-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

--
With best wishes
Dmitry