[PATCH v3 2/4] drm/panel: nt36523: Add DCS backlight support

From: Konrad Dybcio
Date: Mon Apr 17 2023 - 10:39:22 EST


This chip supports controlling the backlight via DCS commands, on at
least some panels. Add support for doing so.

Note this may only concern the NT36523*W* variant. Nobody knows, really,
there's no docs.

Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Reviewed-by: Jianhua Lu <lujianhua000@xxxxxxxxx>
Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
---
drivers/gpu/drm/panel/panel-novatek-nt36523.c | 68 +++++++++++++++++++++++++--
1 file changed, 65 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-novatek-nt36523.c b/drivers/gpu/drm/panel/panel-novatek-nt36523.c
index d30dbbfb67b1..b0466abae812 100644
--- a/drivers/gpu/drm/panel/panel-novatek-nt36523.c
+++ b/drivers/gpu/drm/panel/panel-novatek-nt36523.c
@@ -5,6 +5,7 @@
* Copyright (c) 2022, 2023 Jianhua Lu <lujianhua000@xxxxxxxxx>
*/

+#include <linux/backlight.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
@@ -53,6 +54,7 @@ struct panel_desc {
int (*init_sequence)(struct panel_info *pinfo);

bool is_dual_dsi;
+ bool has_dcs_backlight;
};

static inline struct panel_info *to_panel_info(struct drm_panel *panel)
@@ -679,6 +681,59 @@ static const struct drm_panel_funcs nt36523_panel_funcs = {
.get_modes = nt36523_get_modes,
};

+static int nt36523_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_large(dsi, brightness);
+ if (ret < 0)
+ return ret;
+
+ dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+ return 0;
+}
+
+static int nt36523_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_large(dsi, &brightness);
+ if (ret < 0)
+ return ret;
+
+ dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+ return brightness;
+}
+
+static const struct backlight_ops nt36523_bl_ops = {
+ .update_status = nt36523_bl_update_status,
+ .get_brightness = nt36523_bl_get_brightness,
+};
+
+static struct backlight_device *nt36523_create_backlight(struct mipi_dsi_device *dsi)
+{
+ struct device *dev = &dsi->dev;
+ const struct backlight_properties props = {
+ .type = BACKLIGHT_RAW,
+ .brightness = 512,
+ .max_brightness = 4095,
+ .scale = BACKLIGHT_SCALE_NON_LINEAR,
+ };
+
+ return devm_backlight_device_register(dev, dev_name(dev), dev, dsi,
+ &nt36523_bl_ops, &props);
+}
+
static int nt36523_probe(struct mipi_dsi_device *dsi)
{
struct device *dev = &dsi->dev;
@@ -730,9 +785,16 @@ static int nt36523_probe(struct mipi_dsi_device *dsi)
mipi_dsi_set_drvdata(dsi, pinfo);
drm_panel_init(&pinfo->panel, dev, &nt36523_panel_funcs, DRM_MODE_CONNECTOR_DSI);

- ret = drm_panel_of_backlight(&pinfo->panel);
- if (ret)
- return dev_err_probe(dev, ret, "failed to get backlight\n");
+ if (pinfo->desc->has_dcs_backlight) {
+ pinfo->panel.backlight = nt36523_create_backlight(dsi);
+ if (IS_ERR(pinfo->panel.backlight))
+ return dev_err_probe(dev, PTR_ERR(pinfo->panel.backlight),
+ "Failed to create backlight\n");
+ } else {
+ ret = drm_panel_of_backlight(&pinfo->panel);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to get backlight\n");
+ }

drm_panel_add(&pinfo->panel);


--
2.40.0