drm/panel: visionox-rm69299: Add backlight support

The shift6mq's variant supports controlling the backlight via DSI
commands. Use that if a max_brightness is set in the device specific
data.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250910-shift6mq-panel-v3-3-a7729911afb9@sigxcpu.org

diff --git a/drivers/gpu/drm/panel/panel-visionox-rm69299.c b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
index 66c30db3b73a71f23b587b6e994a22dba5e85d25..e5e688cf98fdc571ae9726f3c9afe7c83db1caf7 100644 (file)
--- a/drivers/gpu/drm/panel/panel-visionox-rm69299.c
+++ b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2019, The Linux Foundation. All rights reserved.
  */
 
+#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/property.h>
@@ -20,6 +21,8 @@ struct visionox_rm69299_panel_desc {
        const struct drm_display_mode *mode;
        const u8 *init_seq;
        unsigned int init_seq_len;
+       int max_brightness;
+       int initial_brightness;
 };
 
 struct visionox_rm69299 {
@@ -285,6 +288,63 @@ static const struct drm_panel_funcs visionox_rm69299_drm_funcs = {
        .get_modes = visionox_rm69299_get_modes,
 };
 
+static int visionox_rm69299_bl_get_brightness(struct backlight_device *bl)
+{
+       struct mipi_dsi_device *dsi = bl_get_data(bl);
+       u16 brightness;
+       int ret;
+
+       dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+       ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+       if (ret < 0)
+               return ret;
+
+       dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+       return brightness;
+}
+
+static int visionox_rm69299_bl_update_status(struct backlight_device *bl)
+{
+       struct mipi_dsi_device *dsi = bl_get_data(bl);
+       u16 brightness = backlight_get_brightness(bl);
+       int ret;
+
+       dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+       ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness);
+       if (ret < 0)
+               return ret;
+
+       dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+       return 0;
+}
+
+static const struct backlight_ops visionox_rm69299_bl_ops = {
+       .update_status = visionox_rm69299_bl_update_status,
+       .get_brightness = visionox_rm69299_bl_get_brightness,
+};
+
+static struct backlight_device *
+visionox_rm69299_create_backlight(struct visionox_rm69299 *ctx)
+{
+       struct device *dev = &ctx->dsi->dev;
+       const struct backlight_properties props = {
+               .type = BACKLIGHT_RAW,
+               .brightness = ctx->desc->initial_brightness,
+               .max_brightness = ctx->desc->max_brightness,
+       };
+
+       if (!ctx->desc->max_brightness)
+               return 0;
+
+       return devm_backlight_device_register(dev, dev_name(dev), dev, ctx->dsi,
+                                             &visionox_rm69299_bl_ops,
+                                             &props);
+}
+
 static int visionox_rm69299_probe(struct mipi_dsi_device *dsi)
 {
        struct device *dev = &dsi->dev;
@@ -316,6 +376,11 @@ static int visionox_rm69299_probe(struct mipi_dsi_device *dsi)
                return PTR_ERR(ctx->reset_gpio);
        }
 
+       ctx->panel.backlight = visionox_rm69299_create_backlight(ctx);
+       if (IS_ERR(ctx->panel.backlight))
+               return dev_err_probe(dev, PTR_ERR(ctx->panel.backlight),
+                                    "Failed to create backlight\n");
+
        drm_panel_add(&ctx->panel);
 
        dsi->lanes = 4;
@@ -353,6 +418,8 @@ const struct visionox_rm69299_panel_desc visionox_rm69299_shift_desc = {
        .mode = &visionox_rm69299_1080x2160_60hz,
        .init_seq = (const u8 *)visionox_rm69299_1080x2160_60hz_init_seq,
        .init_seq_len = ARRAY_SIZE(visionox_rm69299_1080x2160_60hz_init_seq),
+       .max_brightness = 255,
+       .initial_brightness = 50,
 };
 
 static const struct of_device_id visionox_rm69299_of_match[] = {