Re: [PATCH v6 3/5] drm/bridge: analogix_dp: Restore mandatory samsung DP DT properties

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Critical] Failing probe when deprecated DT properties are missing breaks DT ABI and prevents their deprecation.
--

--- Patch [3]: [PATCH v6 3/5] drm/bridge: analogix_dp: Restore mandatory samsung DP DT properties ---
commit b573dba50acc6087122ffa4a65680322f4d004f8
Author: Damon Ding <damon.ding@rock-chips.com>

drm/bridge: analogix_dp: Restore mandatory samsung DP DT properties

This commit reverts a change that made the samsung,link-rate and
samsung,lane-count properties optional for Exynos DP. It adds error checking
to fail the probe early if these properties are missing, aiming to prevent
link training failures caused by zero values.

> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 8cf6b73bceac0..293d8adfe9856 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
[ ... ]
> @@ -1258,10 +1259,14 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
>  		 * NOTE: those property parseing code is used for
>  		 * providing backward compatibility for samsung platform.
>  		 */
> -		of_property_read_u32(dp_node, "samsung,link-rate",
> -				     &video_info->max_link_rate);
> -		of_property_read_u32(dp_node, "samsung,lane-count",
> -				     &video_info->max_lane_count);
> +		if (of_property_read_u32(dp_node, "samsung,link-rate", &val))
> +			return dev_err_probe(dp->dev, -EINVAL,
> +					     "Failed to get samsung,link-rate\n");

[Severity: Critical]
Does failing the probe when this property is missing break the DT ABI?

Since samsung,link-rate is a deprecated property, a modern schema-compliant
Device Tree might intentionally omit it. If a system boots with such a DT,
this check will fail the probe with -EINVAL and disable the display.

Could the driver instead fall back to hardware maximums or sensible defaults
when the deprecated property is absent, rather than returning an error?

> +		video_info->max_link_rate = val;
> +		if (of_property_read_u32(dp_node, "samsung,lane-count", &val))
> +			return dev_err_probe(dp->dev, -EINVAL,
> +					     "Failed to get samsung,lane-count\n");

[Severity: Critical]
Does making samsung,lane-count mandatory similarly break backward compatibility
for valid Device Trees that have intentionally omitted this deprecated property?

> +		video_info->max_lane_count = val;
>  		break;
>  	}
>

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260707040613.1992841-1-damon.ding@rock-chips.com?part=3