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

[Dmitry Baryshkov]

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@xxxxxx>
> Signed-off-by: Aradhya Bhatia <aradhya.bhatia@xxxxxxxxx>
> ---
>  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@xxxxxxxxxx>

-- 
With best wishes
Dmitry