[PATCH v2 2/2] drm/bridge: Document bridge init order with pre_enable_prev_first

[Dave Stevenson]

On Tue, 28 Mar 2023 at 18:08, Jagan Teki <jagan at amarulasolutions.com> wrote:
>
> In order to satisfy the MIPI DSI initialization sequence the bridge
> init order has been altered with the help of pre_enable_prev_first
> in pre_enable and post_disable bridge operations.
>
> Document the affected bridge init order with an example on the
> bridge operations helpers.
>
> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>

Reviewed-by: Dave Stevenson <dave.stevenson at raspberrypi.com>

> ---
> Changes for v2:
> - add missing dri-devel in CC
> - prefix @ for bridge helper names
>
>  drivers/gpu/drm/drm_bridge.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 052a8e6c9961..caf0f341e524 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -654,6 +654,13 @@ static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
>   * bridge will be called before the previous one to reverse the @pre_enable
>   * calling direction.
>   *
> + * Example:
> + * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
> + *
> + * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
> + * @post_disable order would be,
> + * Bridge B, Bridge A, Bridge E, Bridge D, Bridge C.
> + *
>   * Note: the bridge passed should be the one closest to the encoder
>   */
>  void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
> @@ -750,6 +757,13 @@ static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
>   * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
>   * prev bridge will be called before pre_enable of this bridge.
>   *
> + * Example:
> + * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
> + *
> + * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
> + * @pre_enable order would be,
> + * Bridge C, Bridge D, Bridge E, Bridge A, Bridge B.
> + *
>   * Note: the bridge passed should be the one closest to the encoder
>   */
>  void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
> --
> 2.25.1
>