drm/panel: himax-hx83121a: add backlight regulator support

The backlight, when managed by the panel controller, could be powered by
an external regulator, and shutting down the regulator could power off
the backlight.

Add support for such a regulator. It's powered off when the backlight is
0 (either by setting brightness to 0 or setting bl_power), and powered
on when the backlight should be operating.

Signed-off-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260608162622.403713-3-zhengxingda@iscas.ac.cn

diff --git a/drivers/gpu/drm/panel/panel-himax-hx83121a.c b/drivers/gpu/drm/panel/panel-himax-hx83121a.c
index 1a7e0125bced8dd2887d7ab10ec2a608b4b98a24..e31e2fba0a787f646f8a53706368820366c40b94 100644 (file)
--- a/drivers/gpu/drm/panel/panel-himax-hx83121a.c
+++ b/drivers/gpu/drm/panel/panel-himax-hx83121a.c
@@ -34,7 +34,9 @@ struct himax {
        struct drm_dsc_config dsc;
        struct gpio_desc *reset_gpio;
        struct regulator_bulk_data *supplies;
+       struct regulator *bl_supply;
        struct backlight_device *backlight;
+       bool backlight_enabled;
 };
 
 struct panel_desc {
@@ -195,7 +197,27 @@ static int himax_bl_update_status(struct backlight_device *bl)
 {
        struct himax *ctx = bl_get_data(bl);
        u16 brightness = backlight_get_brightness(bl);
+       int ret = 0;
+
+       if (!brightness) {
+               if (ctx->backlight_enabled)
+                       ret = regulator_disable(ctx->bl_supply);
+               if (ret)
+                       return ret;
+
+               ctx->backlight_enabled = false;
+
+               return 0;
+       }
+
        /* TODO: brightness to raw map table */
+       if (!ctx->backlight_enabled)
+               ret = regulator_enable(ctx->bl_supply);
+       if (ret)
+               return ret;
+
+       ctx->backlight_enabled = true;
+
        return mipi_dsi_dcs_set_display_brightness_large(to_primary_dsi(ctx),
                                                         brightness);
 }
@@ -647,6 +669,10 @@ static int himax_probe(struct mipi_dsi_device *dsi)
        ctx->panel.prepare_prev_first = true;
 
        if (desc->has_dcs_backlight) {
+               ctx->bl_supply = devm_regulator_get_optional(dev, "bl");
+               if (IS_ERR(ctx->bl_supply))
+                       return dev_err_probe(dev, PTR_ERR(ctx->bl_supply),
+                                            "Failed to get backlight supply\n");
                ctx->backlight = himax_create_backlight(ctx);
                if (IS_ERR(ctx->backlight))
                        return dev_err_probe(dev, PTR_ERR(ctx->backlight),