Re: [PATCH v11 23/74] drm/display: hdmi-state-helper: Sync SCDC state on hotplug

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] Missing error reporting for drm_edid_connector_update() on the connect path, contradicting the commit message.
- [Low] The SCDC sync call on the disconnect path is a guaranteed no-op, leaving the scrambler state unhandled and introducing dead error-handling code.
--

commit 41a712cbfad2ca468ecdd91cc77914f264d5dce6
Author: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>

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

This commit attempts to synchronize SCDC status on hotplug events by hooking
drm_connector_hdmi_sync_scdc() into the connect and disconnect paths. It also
aims to report errors from drm_edid_connector_update() for consistency.

> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index 8045b1d17d6ec..1e269b203b987 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -1362,12 +1362,29 @@ drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
>  					enum drm_connector_status status)
>  {
>  	const struct drm_edid *drm_edid;
> +	int ret;
>  
>  	if (status == connector_status_disconnected) {
> -		// TODO: also handle scramber, HDMI sink disconnected.
> +		/*
> +		 * .detect_ctx() can only ever return a drm_connector_status or
> +		 * -EDEADLK. Handle deadlocks, and report any !EDEADLK error.
> +		 */
> +		ret = drm_connector_hdmi_sync_scdc(connector, false, ctx);
> +		if (ret) {
> +			if (ret == -EDEADLK)
> +				return ret;
> +
> +			drm_warn(connector->dev, "Ignored SCDC sync error: %d\n", ret);
> +		}

[Severity: Low]
Does this actually handle the scrambler state on disconnect?

If we look at drm_connector_hdmi_sync_scdc(), passing false for the plugged
parameter causes it to return 0 immediately:

int drm_connector_hdmi_sync_scdc(struct drm_connector *connector, bool plugged,
				 struct drm_modeset_acquire_ctx *ctx)
{
	...
	if (!connector || !plugged || !ctx)
		return 0;

Since ret will always be 0, the error handling block here is dead code, and the
scrambler state remains unhandled on the disconnect path.

> +
>  		drm_connector_hdmi_audio_plugged_notify(connector, false);
> -		drm_edid_connector_update(connector, NULL);
> +
> +		ret = drm_edid_connector_update(connector, NULL);
> +		if (ret)
> +			drm_warn(connector->dev, "Ignored EDID update error: %d\n", ret);
> +
>  		drm_connector_cec_phys_addr_invalidate(connector);
> +
>  		return 0;
>  	}
>  

[ ... ]

> @@ -1381,7 +1398,18 @@ drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
>  	drm_edid_free(drm_edid);

[Severity: Medium]
The commit message states that errors from drm_edid_connector_update() will be
reported for consistency.

However, in drm_atomic_helper_connector_hdmi_update(), the return value of the
drm_edid_connector_update() call on the connect path (which happens just before
the drm_edid_free() call in the snippet above) is still being ignored:

	drm_edid_connector_update(connector, drm_edid);
	drm_edid_free(drm_edid);

Should we also add error reporting to this path to match the stated intent?

>  
>  	if (status == connector_status_connected) {
> -		// TODO: also handle scramber, HDMI sink is now connected.
> +		/*
> +		 * .detect_ctx() can only ever return a drm_connector_status or
> +		 * -EDEADLK. Handle deadlocks, and report any !EDEADLK error.
> +		 */
> +		ret = drm_connector_hdmi_sync_scdc(connector, true, ctx);
> +		if (ret) {
> +			if (ret == -EDEADLK)
> +				return ret;
> +
> +			drm_warn(connector->dev, "Ignored SCDC sync error: %d\n", ret);
> +		}
> +
>  		drm_connector_hdmi_audio_plugged_notify(connector, true);
>  		drm_connector_cec_phys_addr_set(connector);
>  	}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260901-dw-hdmi-qp-scramb-v11-0-bc12954a0688@collabora.com?part=23