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

[Marek Vasut]

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;

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