[PATCH v8 10/39] drm/display: hdmi-state-helper: Sync SCDC state on hotplug

[Maxime Ripard]

Hi,

On Thu, Jul 02, 2026 at 05:46:23PM +0300, Cristian Ciocaltea wrote:
> drm_atomic_helper_connector_hdmi_hotplug() does not currently
> synchronize SCDC status on hotplug events, leaving the scrambler state
> potentially inconsistent after (re)connect.
> 
> Hook drm_connector_hdmi_sync_scdc() into both the connect and disconnect
> paths, replacing the existing TODOs around missing scrambler handling.
> 
> SCDC synchronization may require a CRTC reset, which in turn needs a
> modeset acquire context for correct locking.  Therefore, extend
> drm_atomic_helper_connector_hdmi_hotplug() and
> drm_atomic_helper_connector_hdmi_update() to take a
> drm_modeset_acquire_ctx argument.  Additionally, change their return
> type from void to int, allowing propagation of errors, such as -EDEADLK
> from lock contention.
> 
> Update existing callers to pass NULL for the acquire context, preserving
> current behavior.

You should have two patches here: one to change the prototype of the
helpers, and one to add the call to drm_connector_hdmi_sync_scdc


> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea at collabora.com>
> ---
>  drivers/gpu/drm/display/drm_bridge_connector.c  |  3 ++-
>  drivers/gpu/drm/display/drm_hdmi_state_helper.c | 28 +++++++++++++++++--------
>  drivers/gpu/drm/vc4/vc4_hdmi.c                  |  2 +-
>  include/drm/display/drm_hdmi_state_helper.h     |  6 ++++--
>  4 files changed, 26 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
> index 796069dbf1a1..46104506fe32 100644
> --- a/drivers/gpu/drm/display/drm_bridge_connector.c
> +++ b/drivers/gpu/drm/display/drm_bridge_connector.c
> @@ -221,7 +221,8 @@ drm_bridge_connector_detect(struct drm_connector *connector, bool force)
>  		status = detect->funcs->detect(detect, connector);
>  
>  		if (hdmi)
> -			drm_atomic_helper_connector_hdmi_hotplug(connector, status);
> +			drm_atomic_helper_connector_hdmi_hotplug(connector, status,
> +								 NULL);
>  
>  		drm_bridge_connector_hpd_notify(connector, status);
>  	} else {

We should move this one to detect_ctx to get the ctx passed and avoid
passing NULL here.

> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index db76699093e8..69ccfbf123fe 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -1198,18 +1198,20 @@ drm_atomic_helper_connector_hdmi_clear_audio_infoframe(struct drm_connector *con
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_clear_audio_infoframe);
>  
> -static void
> +static int
>  drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
> -					enum drm_connector_status status)
> +					enum drm_connector_status status,
> +					struct drm_modeset_acquire_ctx *ctx)

detect_ctx has the context first, I think we should use that convention
here too.

>  {
>  	const struct drm_edid *drm_edid;
> +	int ret = 0;
>  
>  	if (status == connector_status_disconnected) {
> -		// TODO: also handle scramber, HDMI sink disconnected.
> +		ret = drm_connector_hdmi_sync_scdc(connector, false, ctx);
>  		drm_connector_hdmi_audio_plugged_notify(connector, false);
>  		drm_edid_connector_update(connector, NULL);
>  		drm_connector_cec_phys_addr_invalidate(connector);
> -		return;
> +		return ret;
>  	}
>  
>  	if (connector->hdmi.funcs->read_edid)
> @@ -1222,24 +1224,32 @@ drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
>  	drm_edid_free(drm_edid);
>  
>  	if (status == connector_status_connected) {
> -		// TODO: also handle scramber, HDMI sink is now connected.
> +		ret = drm_connector_hdmi_sync_scdc(connector, true, ctx);
>  		drm_connector_hdmi_audio_plugged_notify(connector, true);
>  		drm_connector_cec_phys_addr_set(connector);
>  	}
> +
> +	return ret;
>  }
>  
>  /**
>   * drm_atomic_helper_connector_hdmi_hotplug - Handle the hotplug event for the HDMI connector
>   * @connector: A pointer to the HDMI connector
>   * @status: Connection status
> + * @ctx: Lock acquisition context to be used for resetting CRTC
>   *
>   * This function should be called as a part of the .detect() / .detect_ctx()
>   * callbacks for all status changes.
> + *
> + * Returns:
> + * Zero on success, error code on failure.
> + * If @ctx is set, it might also return -EDEADLK.
>   */
> -void drm_atomic_helper_connector_hdmi_hotplug(struct drm_connector *connector,
> -					      enum drm_connector_status status)
> +int drm_atomic_helper_connector_hdmi_hotplug(struct drm_connector *connector,
> +					     enum drm_connector_status status,
> +					     struct drm_modeset_acquire_ctx *ctx)
>  {
> -	drm_atomic_helper_connector_hdmi_update(connector, status);
> +	return drm_atomic_helper_connector_hdmi_update(connector, status, ctx);
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_hotplug);
>  
> @@ -1254,6 +1264,6 @@ EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_hotplug);
>   */
>  void drm_atomic_helper_connector_hdmi_force(struct drm_connector *connector)
>  {
> -	drm_atomic_helper_connector_hdmi_update(connector, connector->status);
> +	drm_atomic_helper_connector_hdmi_update(connector, connector->status, NULL);
>  }

We should create a new context here.

>  EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_force);
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 74dce4be0c00..e165f604939b 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -375,7 +375,7 @@ static void vc4_hdmi_handle_hotplug(struct vc4_hdmi *vc4_hdmi,
>  	 * the lock for now.
>  	 */
>  
> -	drm_atomic_helper_connector_hdmi_hotplug(connector, status);
> +	drm_atomic_helper_connector_hdmi_hotplug(connector, status, NULL);

vc4_hdmi_handle_hotplug has the context passed as an argument, we should reuse it.

Maxime
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