diff mbox series

[v9,17/61] drm/display: hdmi-state-helper: Sync SCDC state on hotplug

Message ID 20260723-dw-hdmi-qp-scramb-v9-17-4fb12ea22ac9@collabora.com (mailing list archive)
State New
Headers
Series Add HDMI 2.0 support to DW HDMI QP TX |

Commit Message

Cristian Ciocaltea July 23, 2026, 1:35 a.m. UTC 
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.

Tested-by: Maud Spierings <maud_spierings@hotmail.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/display/drm_hdmi_state_helper.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

Comments

sashiko-bot@kernel.org July 23, 2026, 1:53 a.m. UTC | #1 
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The HDMI disconnect path fails to implement SCDC scrambler synchronization, resulting in dead code and potential display corruption on hotplug.
--

--- Patch [17]: [PATCH v9 17/61] drm/display: hdmi-state-helper: Sync SCDC state on hotplug ---
commit c0cc8e9a78dd0bbc36a54e19e44a65a37553ae23
Author: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>

drm/display: hdmi-state-helper: Sync SCDC state on hotplug

This commit hooks drm_connector_hdmi_sync_scdc() into both the connect and
disconnect paths in drm_atomic_helper_connector_hdmi_update() to synchronize
the SCDC status on hotplug events.

> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index 04d5196a2010f..ad59318a3e85f 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -1205,13 +1205,16 @@ drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
>  					enum drm_connector_status status)
>  {
>  	const struct drm_edid *drm_edid;
> +	int ret = 0;
>  
>  	if (status == connector_status_disconnected) {
> -		// TODO: also handle scramber, HDMI sink disconnected.
> -		drm_connector_hdmi_audio_plugged_notify(connector, false);
> -		drm_edid_connector_update(connector, NULL);
> -		drm_connector_cec_phys_addr_invalidate(connector);
> -		return 0;
> +		ret = drm_connector_hdmi_sync_scdc(connector, false, ctx);
> +		if (ret != -EDEADLK) {

[Severity: Medium]
Does this code actually synchronize the scrambler on disconnect?

Looking at drm_connector_hdmi_sync_scdc(), it has an early return when
plugged is false:

drivers/gpu/drm/display/drm_hdmi_helper.c:drm_connector_hdmi_sync_scdc() {
	...
	if (!connector || !plugged || !ctx)
		return 0;
	...
}

Because of this early return, calling drm_connector_hdmi_sync_scdc() with
false for the plugged parameter makes it a no-op, which bypasses the
scrambler synchronization logic.

Additionally, since it always returns 0 in this case, doesn't this make the
if (ret != -EDEADLK) check dead code?

> +			drm_connector_hdmi_audio_plugged_notify(connector, false);
> +			drm_edid_connector_update(connector, NULL);
> +			drm_connector_cec_phys_addr_invalidate(connector);
> +		}
> +		return ret;
>  	}
>  

[ ... ]
diff mbox series

Patch

diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index 04d5196a2010..ad59318a3e85 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -1205,13 +1205,16 @@  drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
 					enum drm_connector_status status)
 {
 	const struct drm_edid *drm_edid;
+	int ret = 0;
 
 	if (status == connector_status_disconnected) {
-		// TODO: also handle scramber, HDMI sink disconnected.
-		drm_connector_hdmi_audio_plugged_notify(connector, false);
-		drm_edid_connector_update(connector, NULL);
-		drm_connector_cec_phys_addr_invalidate(connector);
-		return 0;
+		ret = drm_connector_hdmi_sync_scdc(connector, false, ctx);
+		if (ret != -EDEADLK) {
+			drm_connector_hdmi_audio_plugged_notify(connector, false);
+			drm_edid_connector_update(connector, NULL);
+			drm_connector_cec_phys_addr_invalidate(connector);
+		}
+		return ret;
 	}
 
 	if (connector->hdmi.funcs->read_edid)
@@ -1224,12 +1227,14 @@  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.
-		drm_connector_hdmi_audio_plugged_notify(connector, true);
-		drm_connector_cec_phys_addr_set(connector);
+		ret = drm_connector_hdmi_sync_scdc(connector, true, ctx);
+		if (ret != -EDEADLK) {
+			drm_connector_hdmi_audio_plugged_notify(connector, true);
+			drm_connector_cec_phys_addr_set(connector);
+		}
 	}
 
-	return 0;
+	return ret;
 }
 
 /**