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

Tomi Valkeinen
2025-02-04T13:41:29Z

Hi,

On 26/01/2025 21:15, 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(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index f5532e3646e1..d2f19df9f418 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1298,9 +1298,9 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
> {
> encoder_bridge_disable(dev, old_state);
>
> - encoder_bridge_post_disable(dev, old_state);
> -
> crtc_disable(dev, old_state);
> +
> + encoder_bridge_post_disable(dev, old_state);
> }
>
> /**
> @@ -1635,10 +1635,10 @@ encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *old_state
> void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
> struct drm_atomic_state *old_state)
> {
> - crtc_enable(dev, old_state);
> -
> encoder_bridge_pre_enable(dev, old_state);
>
> + crtc_enable(dev, old_state);
> +
> encoder_bridge_enable(dev, old_state);
>
> drm_atomic_helper_commit_writebacks(dev, old_state);

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Tomi