Re: [PATCH v3 1/2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Probe definitively fails on valid legacy 3-lane or 0-indexed device trees due to rigid array bounds.
--

--- Patch [1]: [PATCH v3 1/2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support ---
commit 47fc41c5744e78e6f8072b1226e9548c69361da5
Author: Wojciech Dubowik <Wojciech.Dubowik@mt.com>

drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support

The chip supports output lvds lanes in two orders, default <1 2 3 4>
and <4 3 2 1>. Add parsing of an optional output lvds data-lanes
property so we can inform chip that the lanes have been reversed.

> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
[ ... ]
> @@ -854,6 +873,37 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
>  		goto exit;
>  	}
>  
> +	ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
> +			ARRAY_SIZE(data_lanes));
> +	if (ret_data != 0 && ret_data != -EINVAL) {

[Severity: High]
Does this code break valid legacy device trees that define fewer than 4 lanes?

If a device tree has a data-lanes property on the LVDS endpoint with fewer
than 4 lanes (e.g., <1 2 3>), of_property_read_u32_array() will return
-EOVERFLOW because it rigidly expects exactly ARRAY_SIZE(data_lanes) elements.
This will immediately abort the probe, breaking previously working displays.

> +		ret = ret_data;
> +		goto exit;
> +	}
> +
> +	if (!ret_data) {
> +		for (i = 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
> +			for (j = 0; j < DATA_LANES_COUNT; j++) {
> +				if (data_lanes[j] != supported_data_lane_mapping[i][j])
> +					break;
> +			}
> +
> +			if (j == DATA_LANES_COUNT)
> +				break;
> +		}
> +
> +		switch (i) {
> +		case NORMAL_LANE_MAPPING:
> +			break;
> +		case REVERSE_LANE_MAPPING:
> +			ctx->lvds_reverse_lanes_conf[channel] = true;
> +			break;
> +		default:
> +			dev_err(dev, "invalid data lanes mapping\n");
> +			ret = -EINVAL;

[Severity: High]
Will this cause the probe to fail on 0-indexed device tree configurations?

The array comparison logic above this switch strictly checks for 1-indexed
mappings. If the device tree uses a valid 0-indexed scheme (e.g., <0 1 2 3>),
it falls through to this default case, causing the probe to fail with -EINVAL.

> +			goto exit;
> +		}
> +	}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260710082630.394040-1-wojciech.dubowik@mt.com?part=1