Re: [PATCH v5 3/3] 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:
- [Medium] `memcmp()` is called with `ARRAY_SIZE(data_lanes)` instead of `sizeof(data_lanes)`, causing it to compare only the first element of the `u32` array.
--

--- Patch [3]: [PATCH v5 3/3] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support ---
commit 5b0901160799f83c03f127b68580169dd845ac90
Author: Wojciech Dubowik <Wojciech.Dubowik@mt.com>

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

This commit adds support for parsing an optional "data-lanes" device tree
property. It allows the driver to configure the ti-sn65dsi83 chip for
reversed output LVDS lane order.

> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index f8a786953526d..df44df2e872af 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c

[ ... ]

> @@ -845,6 +863,19 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
>  	else
>  		return -EINVAL;
>  
> +	ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
> +			ARRAY_SIZE(data_lanes));
> +	if (!ret_data) {
> +		if (memcmp(data_lanes,
> +				supported_data_lane_mapping[LANE_MAPPING_REVERSE],
> +				ARRAY_SIZE(data_lanes)) == 0)

[Severity: Medium]
Does this code compare the entire array? memcmp() expects the length in
bytes, but ARRAY_SIZE(data_lanes) evaluates to 4 (the number of elements).

Because data_lanes is an array of u32, checking only 4 bytes means only
the first element is compared. Should this be using sizeof(data_lanes)
instead?

> +			ctx->lvds_reverse_lanes_conf[channel] = true;
> +		else if (memcmp(data_lanes,
> +			   supported_data_lane_mapping[LANE_MAPPING_NORMAL],
> +			   ARRAY_SIZE(data_lanes)) != 0)

[Severity: Medium]
The same question applies here. Because only the first element is verified,
would an invalid device tree configuration like <4 0 0 0> erroneously match
LANE_MAPPING_REVERSE and bypass the expected validation?

> +			return dev_err_probe(dev, -EINVAL, "invalid data lanes mapping\n");
> +	}
> +
>  	ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
>  					lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260717115002.308035-1-wojciech.dubowik@mt.com?part=3