On Mon, Nov 02, 2026 at 09:58:49PM +0200, Roman Vivchar via B4 Relay wrote:
> From: Roman Vivchar <[email protected]>
>
> 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 <[email protected]>
> ---
> 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 <[email protected]>
> S: Maintained
> F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd3137.yaml
> +F: drivers/video/backlight/ktd3137.c
>
> KTEST
> M: Steven Rostedt <[email protected]>
> 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
> @@ -0,0 +1,262 @@
> <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.
> + 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()
> +
> + 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.
