Re: [PATCH 2/2] drm/bridge: lt9211: Add drive-strength-microamp DT property

[Marek Vasut <marex@nabladev.com>]

On 5/12/26 6:46 PM, Boerge Struempfel wrote:

> +/* Maps register value (index) to drive-strength-microamp DT property value */
> +static const u32 lt9211_hsdrv_microamp[] = {

This can be u8 .

> +	12, 14, 16, 17, 19, 20, 22, 23, 25, 27, 28, 30, 31, 33, 34, 36
> +};
> +
>   struct lt9211 {
>   	struct drm_bridge		bridge;
>   	struct device			*dev;
> @@ -50,6 +55,7 @@ struct lt9211 {
>   	struct regulator		*vccio;
>   	bool				lvds_dual_link;
>   	bool				lvds_dual_link_even_odd_swap;
> +	u8				lvds_hsdrv_isel;
>   };
>   
>   static const struct regmap_range lt9211_rw_ranges[] = {
> @@ -374,7 +380,8 @@ static int lt9211_configure_tx(struct lt9211 *ctx, bool jeida,
>   		/* BIT(7) is LVDS dual-port */
>   		{ 0x823b, 0x38 | (ctx->lvds_dual_link ? BIT(7) : 0) },
>   		{ 0x823e, 0x92 },
> -		{ 0x823f, 0x48 },
> +		/* bits 3:0: RG_MLTX_HSDRV_ISEL, LVDS TX driver current */
> +		{ 0x823f, 0x40 | ctx->lvds_hsdrv_isel },
>   		{ 0x8240, 0x31 },
>   		{ 0x8243, 0x80 },
>   		{ 0x8244, 0x00 },
> @@ -629,7 +636,9 @@ static int lt9211_parse_dt(struct lt9211 *ctx)
>   	struct device *dev = ctx->dev;
>   	struct drm_panel *panel;
>   	int dual_link;
> +	u32 microamp;
>   	int ret;
> +	int i;
>   
>   	ctx->vccio = devm_regulator_get(dev, "vccio");
>   	if (IS_ERR(ctx->vccio))
> @@ -666,6 +675,23 @@ static int lt9211_parse_dt(struct lt9211 *ctx)
>   
>   	ctx->panel_bridge = panel_bridge;
>   
> +	ctx->lvds_hsdrv_isel = 8; /* default: 25 uA */
> +	ret = of_property_read_u32(dev->of_node, "drive-strength-microamp",
> +				   &microamp);

if ret != 0 , then what happens here ?

> +	if (!ret) {
> +		for (i = 0; i < ARRAY_SIZE(lt9211_hsdrv_microamp); i++) {
> +			if (lt9211_hsdrv_microamp[i] == microamp) {
> +				ctx->lvds_hsdrv_isel = i;
> +				break;
> +			}
> +		}
> +		if (i == ARRAY_SIZE(lt9211_hsdrv_microamp)) {
> +			dev_err(dev, "Invalid drive-strength-microamp value %u\n",
> +				microamp);
> +			return -EINVAL;
> +		}
> +	}
> +
>   	return 0;
[...]