On Mon, Nov 02, 2026 at 09:58:49PM +0200, Roman Vivchar via B4 Relay wrote:
quoted hunk ↗ jump to hunk
From: Roman Vivchar <rva333@protonmail.com>
Add support for the KTD3137 display backlight IC. It's used in various
Xiaomi phones, such as Xiaomi Redmi Note 9.
Signed-off-by: Roman Vivchar <rva333@protonmail.com>
---
MAINTAINERS | 1 +
drivers/video/backlight/Kconfig | 11 ++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/ktd3137.c | 262 ++++++++++++++++++++++++++++++++++++++
4 files changed, 275 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 24dd5b43f167..23114fd09445 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14622,6 +14622,7 @@ KTD3137 BACKLIGHT DRIVER
M: Roman Vivchar <rva333@protonmail.com>
S: Maintained
F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd3137.yaml
+F: drivers/video/backlight/ktd3137.c
KTEST
M: Steven Rostedt <rostedt@goodmis.org>
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 7c66b8840d88..0196b8597367 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -199,6 +199,17 @@ config BACKLIGHT_KTD2801
Say Y to enable the backlight driver for the Kinetic KTD2801 1-wire
GPIO-controlled backlight found in Samsung Galaxy Core Prime VE LTE.
+config BACKLIGHT_KTD3137
+ tristate "Backlight Driver for Kinetic KTD3137"
+ depends on I2C
+ select REGMAP_I2C
+ help
+ Say Y to enable the backlight driver for the Kinetic KTD3137
+ found in various Xiaomi smartphones.
+
+ To compile this driver as a module, choose M here: the module
+ will be called ktd3137.
+
config BACKLIGHT_KTZ8866
tristate "Backlight Driver for Kinetic KTZ8866"
depends on I2C
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 34469711c6cd..b2d3b69e9e32 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_BACKLIGHT_HP700) += jornada720_bl.o
obj-$(CONFIG_BACKLIGHT_IPAQ_MICRO) += ipaq_micro_bl.o
obj-$(CONFIG_BACKLIGHT_KTD253) += ktd253-backlight.o
obj-$(CONFIG_BACKLIGHT_KTD2801) += ktd2801-backlight.o
+obj-$(CONFIG_BACKLIGHT_KTD3137) += ktd3137.o
obj-$(CONFIG_BACKLIGHT_KTZ8866) += ktz8866.o
obj-$(CONFIG_BACKLIGHT_LM3509) += lm3509_bl.o
obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_bl.o
diff --git a/drivers/video/backlight/ktd3137.c b/drivers/video/backlight/ktd3137.c
new file mode 100644
index 000000000000..a3ff334b8d46
--- /dev/null
+++ b/drivers/video/backlight/ktd3137.c
<snip>
+static int ktd3137_init(struct ktd3137 *ktd)
+{
+ u32 val = KTD3137_CONTROL_DEFAULT | KTD3137_CONTROL_LINEAR;
+ int ret;
+
+ ret = regmap_write(ktd->regmap, KTD3137_REG_CONTROL, val);
Nitpicking but val seems a bit pointless here.
+ if (ret)
+ return ret;
+
+ ret = regmap_write(ktd->regmap, KTD3137_REG_PWM, KTD3137_PWM_DEFAULT);
+ if (ret)
+ return ret;
+
+ ret = regmap_write(ktd->regmap, KTD3137_REG_RAMP_ON, KTD3137_RAMP_DEFAULT);
+ if (ret)
+ return ret;
+
+ ret = regmap_write(ktd->regmap, KTD3137_REG_TRANS_RAMP, 0x00);
+ if (ret)
+ return ret;
+
+ return regmap_update_bits(ktd->regmap, KTD3137_REG_MODE,
+ KTD3137_MODE_CURRENT_MASK, ktd->led_current);
+}
<snip>
+static int ktd3137_probe(struct i2c_client *client)
+{
+ struct backlight_device *backlight_dev;
+ struct backlight_properties props = { };
+ struct ktd3137 *ktd;
+ u32 val;
+ int ret;
+
+ ktd = devm_kzalloc(&client->dev, sizeof(*ktd), GFP_KERNEL);
+ if (!ktd)
+ return -ENOMEM;
+
+ ktd->dev = &client->dev;
+
+ ret = devm_regulator_get_enable(ktd->dev, "vin");
+ if (ret)
+ return dev_err_probe(ktd->dev, ret, "failed to power up\n");
+
+ ktd->enable_gpio = devm_gpiod_get_optional(ktd->dev, "enable",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(ktd->enable_gpio))
+ return dev_err_probe(ktd->dev, PTR_ERR(ktd->enable_gpio),
+ "failed to get enable gpio\n");
+
+ /* HWEN should stay HIGH for at least 150us before I2C can be used */
+ fsleep(150);
+
+ ktd->regmap = devm_regmap_init_i2c(client, &ktd3137_regmap_config);
+ if (IS_ERR(ktd->regmap))
+ return dev_err_probe(ktd->dev, PTR_ERR(ktd->regmap),
+ "failed to init regmap\n");
+
+ ret = regmap_read(ktd->regmap, KTD3137_REG_DEV_ID, &val);
+ if (ret)
+ return dev_err_probe(ktd->dev, ret, "failed to read chip id\n");
+
+ if (val != KTD3137_DEV_ID_A && val != KTD3137_DEV_ID_B)
+ return dev_err_probe(ktd->dev, -ENODEV,
+ "unsupported chip id: 0x%02x\n", val);
+
+ ret = ktd3137_parse_dt(ktd);
+ if (ret)
+ return ret;
+
+ ret = ktd3137_init(ktd);
+ if (ret)
+ return dev_err_probe(ktd->dev, ret, "failed to init chip\n");
+
+ props.type = BACKLIGHT_RAW;
+ props.max_brightness = KTD3137_MAX_BRIGHTNESS;
+ props.brightness = KTD3137_DEFAULT_BRIGHTNESS;
No need for KTD3137_DEFAULT_BRIGHTNESS. Just use KTD3137_MAX_BRIGHTNESS.
quoted hunk ↗ jump to hunk
+ props.scale = BACKLIGHT_SCALE_LINEAR;
+ device_property_read_u32(ktd->dev, "default-brightness", &props.brightness);
+
+ backlight_dev = devm_backlight_device_register(ktd->dev,
+ "ktd3137-backlight",
+ ktd->dev, ktd,
+ &ktd3137_backlight_ops,
+ &props);
+ if (IS_ERR(backlight_dev))
+ return dev_err_probe(ktd->dev, PTR_ERR(backlight_dev),
+ "failed to register backlight device\n");
dev_err_cast_probe()
quoted hunk ↗ jump to hunk
+
+ i2c_set_clientdata(client, backlight_dev);
+ return backlight_update_status(backlight_dev);
+}
+
+static void ktd3137_remove(struct i2c_client *client)
+{
+ struct backlight_device *backlight_dev = i2c_get_clientdata(client);
+ struct ktd3137 *ktd = bl_get_data(backlight_dev);
+
+ backlight_dev->props.brightness = 0;
+ backlight_update_status(backlight_dev);
+
+ gpiod_set_value_cansleep(ktd->enable_gpio, 0);
Is this needed?
+}
Daniel.