[PATCH v2 0/2] backlight: Add SY7758 6-channel High Efficiency LED Driver support

[PATCH v2 0/2] backlight: Add SY7758 6-channel High Efficiency LED Driver support

[Neil Armstrong]

Implement support for the Silergy SY7758 6-channel High Efficiency LED Driver
used for backlight brightness control in the Ayaneo Pocket S2 dual-DSI panel.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
Changes in v2:
- Fixed bindings subject and removed "|"
- Added review tag
- Added higher delay before reading ID from HW (100us was too short)
- Removed probe defer if i2c read fails
- Link to v1: https://patch.msgid.link/20260428-topic-sm8650-ayaneo-pocket-s2-sy7758-v1-0-0caade5fdb32@linaro.org

---
KancyJoe (1):
      backlight: Add SY7758 6-channel High Efficiency LED Driver support

Neil Armstrong (1):
      dt-bindings: leds: backlight: document the SY7758 6-channel High Efficiency LED Driver

 .../bindings/leds/backlight/silergy,sy7758.yaml    |  53 ++++
 drivers/video/backlight/Kconfig                    |   8 +
 drivers/video/backlight/Makefile                   |   1 +
 drivers/video/backlight/sy7758.c                   | 311 +++++++++++++++++++++
 4 files changed, 373 insertions(+)
---
base-commit: 39704f00f747aba3144289870b5fd8ac230a9aaf
change-id: 20260428-topic-sm8650-ayaneo-pocket-s2-sy7758-3081ee7f1e25

Best regards,
--  
Neil Armstrong <neil.armstrong@linaro.org>

[PATCH v2 1/2] dt-bindings: leds: backlight: document the SY7758 6-channel High Efficiency LED Driver

[Neil Armstrong]

Document the Silergy SY7758 6-channel High Efficiency LED Driver
used for backlight brightness control.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 .../bindings/leds/backlight/silergy,sy7758.yaml    | 53 ++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/silergy,sy7758.yaml b/Documentation/devicetree/bindings/leds/backlight/silergy,sy7758.yaml
new file mode 100644
index 000000000000..80e978d691c2
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/silergy,sy7758.yaml
@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/silergy,sy7758.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Silergy SY7758 6-channel High Efficiency LED Driver
+
+maintainers:
+  - Neil Armstrong <neil.armstrong@linaro.org>
+
+description:
+  Silergy SY7758 is a high efficiency 6-channels LED backlight
+  driver with I2C brightness control.
+
+allOf:
+  - $ref: common.yaml#
+
+properties:
+  compatible:
+    const: silergy,sy7758
+
+  reg:
+    maxItems: 1
+
+  vddio-supply: true
+
+  enable-gpios:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - vddio-supply
+  - enable-gpios
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        backlight@11 {
+            compatible = "silergy,sy7758";
+            reg = <0x11>;
+            vddio-supply = <&bl_vddio>;
+            enable-gpios = <&gpio 16 GPIO_ACTIVE_HIGH>;
+        };
+    };

-- 
2.34.1

Re: [PATCH v2 1/2] dt-bindings: leds: backlight: document the SY7758 6-channel High Efficiency LED Driver

[Daniel Thompson]

On Thu, Apr 30, 2026 at 11:47:15AM +0200, Neil Armstrong wrote:
> Document the Silergy SY7758 6-channel High Efficiency LED Driver
> used for backlight brightness control.
>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>


Daniel.

[PATCH v2 2/2] backlight: Add SY7758 6-channel High Efficiency LED Driver support

[Neil Armstrong]

From: KancyJoe <kancy2333@outlook.com>

Implement support for the Silergy SY7758 6-channel High Efficiency LED
Driver used for backlight brightness control in the Ayaneo Pocket S2
dual-DSI panel.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: KancyJoe <kancy2333@outlook.com>
---
 drivers/video/backlight/Kconfig  |   8 +
 drivers/video/backlight/Makefile |   1 +
 drivers/video/backlight/sy7758.c | 311 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 320 insertions(+)

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index a7a3fbaf7c29..052ac80c8213 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -207,6 +207,14 @@ config BACKLIGHT_KTZ8866
 		Say Y to enable the backlight driver for the Kinetic KTZ8866
 		found in Xiaomi Mi Pad 5 series.
 
+config BACKLIGHT_SY7758
+	tristate "Backlight Driver for Silergy SY7758"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say Y to enable the backlight driver for the Silergy SY7758
+	  backlight controller found in Ayaneo Socket S2.
+
 config BACKLIGHT_LM3533
 	tristate "Backlight Driver for LM3533"
 	depends on MFD_LM3533
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 794820a98ed4..39ef588b1cf2 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_BACKLIGHT_PWM)		+= pwm_bl.o
 obj-$(CONFIG_BACKLIGHT_QCOM_WLED)	+= qcom-wled.o
 obj-$(CONFIG_BACKLIGHT_RT4831)		+= rt4831-backlight.o
 obj-$(CONFIG_BACKLIGHT_SAHARA)		+= kb3886_bl.o
+obj-$(CONFIG_BACKLIGHT_SY7758)		+= sy7758.o
 obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
diff --git a/drivers/video/backlight/sy7758.c b/drivers/video/backlight/sy7758.c
new file mode 100644
index 000000000000..9b2d3bbb4ded
--- /dev/null
+++ b/drivers/video/backlight/sy7758.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Silergy SY7758 6-channel High Efficiency LED Driver
+ *
+ * Copyright (C) 2025 Kancy Joe <kancy2333@outlook.com>
+ * Copyright (C) 2026 Linaro Limited
+ * Author: Neil Armstrong <neil.armstrong@linaro.org>
+ */
+#include <linux/backlight.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/err.h>
+#include <linux/bits.h>
+#include <linux/regmap.h>
+#include <linux/bitfield.h>
+#include <linux/gpio/consumer.h>
+#include <linux/regulator/consumer.h>
+
+#define DEFAULT_BRIGHTNESS 1024
+#define MAX_BRIGHTNESS 4080
+#define REG_MAX 0xAE
+
+/* Registers */
+#define REG_BRT_8BIT 0x00
+#define REG_DEV_CTL 0x01
+#define REG_STATUS 0x02
+#define REG_DEV_ID 0x03
+#define REG_DIRECT_CTL 0x04
+#define REG_STATUS2 0x05
+#define REG_BRT_12BIT_L 0x10
+#define REG_BRT_12BIT_H 0x11
+#define REG_LED_ENABLE 0x16
+
+/* OTP memory */
+#define REG_OTP_CFG98 0x98
+#define REG_OTP_CFG9E 0x9E
+#define REG_OTP_CFG0 0xA0
+#define REG_OTP_CFG1 0xA1
+#define REG_OTP_CFG2 0xA2
+#define REG_OTP_CFG3 0xA3
+#define REG_OTP_CFG4 0xA4
+#define REG_OTP_CFG5 0xA5
+#define REG_OTP_CFG6 0xA6
+#define REG_OTP_CFG7 0xA7
+#define REG_OTP_CFG9 0xA9
+#define REG_OTP_CFGA 0xAA
+#define REG_OTP_CFGE 0xAE
+
+/* Fields */
+#define BIT_DEV_CTL_FAST BIT(7)
+#define MSK_DEV_CTL_BRT_MODE GENMASK(2, 1)
+#define BIT_DEV_CTL_BL_CTLB BIT(0)
+
+#define BIT_STATUS_OPEN BIT(7)
+#define BIT_STATUS_SHORT BIT(6)
+#define BIT_STATUS_VREF_OK BIT(5)
+#define BIT_STATUS_VBST_OK BIT(4)
+#define BIT_STATUS_OVP BIT(3)
+#define BIT_STATUS_OCP BIT(2)
+#define BIT_STATUS_TSD BIT(1)
+#define BIT_STATUS_UVLO BIT(0)
+
+#define MSK_DIRECT_CTL_OUT GENMASK(5, 0)
+
+#define BIT_STATUS2_OCP50MS_LATCH BIT(0)
+#define BIT_STATUS2_OCP2 BIT(0)
+
+#define MSK_BRT_12BIT_L GENMASK(7, 0)
+#define MSK_BRT_12BIT_H GENMASK(3, 0)
+#define MSK_LED_ENABLE GENMASK(5, 0)
+
+#define BIT_CFG98_IBST_LIM_2X BIT(7)
+#define BIT_CFG98_A0_FSETB BIT(0)
+
+#define BIT_CFG9E_VBST_RANGE BIT(5)
+#define MSK_CFG9E_HEADROOM_OFFSET GENMASK(3, 0)
+
+#define MSK_CFG0_CURRENT_LOW GENMASK(7, 0)
+
+#define BIT_CFG1_PDET_STDBY BIT(7)
+#define MSK_CFG1_CURRENT_MAX GENMASK(6, 4)
+#define MSK_CFG1_CURRENT_HIGH GENMASK(3, 0)
+
+#define BIT_CFG2_UVLO_EN BIT(5)
+#define BIT_CFG2_UVLO_TH BIT(4)
+#define BIT_CFG2_BL_ON BIT(3)
+#define BIT_CFG2_ISET_EN BIT(2)
+#define BIT_CFG2_BST_ESET_EN BIT(1)
+
+#define MSK_CFG3_SLOPE GENMASK(6, 4)
+#define MSK_CFG3_FILTER GENMASK(3, 2)
+#define MSK_CFG3_PWM_INPUT_HYSTERESIS GENMASK(1, 0)
+#define MSK_CFG4_PWM_TO_I_TH GENMASK(7, 4)
+
+#define BIT_CFG5_PWM_DIRECT BIT(7)
+#define MSK_CFG5_PS_MODE GENMASK(6, 4)
+#define MSK_CFG5_PWM_FREQ GENMASK(3, 0)
+
+#define MSK_CFG6_BST_FREQ GENMASK(7, 6)
+#define MSK_CFG6_VBST GENMASK(5, 0)
+
+#define BIT_CFG7_EN_DRV3 BIT(5)
+#define BIT_CFG7_EN_DRV2 BIT(4)
+#define MSK_CFG7_IBST_LIM GENMASK(1, 0)
+
+#define MSK_CFG9_VBST_MAX GENMASK(7, 5)
+#define BIT_CFG9_JUMP_EN BIT(4)
+#define MSK_CFG9_JUMP_TH GENMASK(3, 2)
+#define MSK_CFG9_JUMP_VOLTAGE GENMASK(1, 0)
+
+#define BIT_CFGA_SSCLK_EN BIT(7)
+#define BIT_CFGA_ADAPTIVE BIT(3)
+#define MSK_CFGA_DRIVER_HEADROOM GENMASK(2, 0)
+#define MSK_CFGE_STEP_UP GENMASK(7, 6)
+#define MSK_CFGE_STEP_DN GENMASK(5, 4)
+#define MSK_CFGE_LED_FAULT_TH GENMASK(3, 2)
+#define MSK_CFGE_LED_COMP_HYST GENMASK(1, 0)
+
+struct sy7758 {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct gpio_desc *gpio;
+	struct backlight_device *bl;
+};
+
+static const struct regmap_config sy7758_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = REG_MAX,
+};
+
+static int sy7758_backlight_update_status(struct backlight_device *backlight_dev)
+{
+	struct sy7758 *sydev = bl_get_data(backlight_dev);
+	unsigned int brightness = backlight_get_brightness(backlight_dev);
+	int ret;
+
+	ret = regmap_write(sydev->regmap, REG_BRT_12BIT_L,
+			   FIELD_PREP(MSK_BRT_12BIT_L,
+				      brightness & 0xff));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_BRT_12BIT_H,
+			   FIELD_PREP(MSK_BRT_12BIT_H,
+				      (brightness >> 8) & 0xf));
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct backlight_ops sy7758_backlight_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = sy7758_backlight_update_status,
+};
+
+static int sy7758_init(struct sy7758 *sydev)
+{
+	int ret = 0;
+
+	ret = regmap_write(sydev->regmap, REG_DEV_CTL,
+			   BIT_DEV_CTL_FAST | BIT_DEV_CTL_BL_CTLB |
+			   FIELD_PREP(MSK_DEV_CTL_BRT_MODE, 2));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_BRT_12BIT_L,
+			   FIELD_PREP(MSK_BRT_12BIT_L,
+				      DEFAULT_BRIGHTNESS & 0xff));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_BRT_12BIT_H,
+			   FIELD_PREP(MSK_BRT_12BIT_H,
+				      (DEFAULT_BRIGHTNESS >> 8)));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_OTP_CFG5,
+			   FIELD_PREP(MSK_CFG5_PS_MODE, 6) |
+			   FIELD_PREP(MSK_CFG5_PWM_FREQ, 4));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_OTP_CFG0,
+			   FIELD_PREP(MSK_CFG0_CURRENT_LOW, 85));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_OTP_CFG1,
+			   BIT_CFG1_PDET_STDBY |
+			   FIELD_PREP(MSK_CFG1_CURRENT_MAX, 1) |
+			   FIELD_PREP(MSK_CFG1_CURRENT_HIGH, 10));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_OTP_CFG9,
+			   FIELD_PREP(MSK_CFG9_VBST_MAX, 4));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(sydev->regmap, REG_OTP_CFG2,
+			   BIT_CFG2_BL_ON | BIT_CFG2_UVLO_EN);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int sy7758_probe(struct i2c_client *client)
+{
+	struct backlight_properties props = { };
+	struct device *dev = &client->dev;
+	struct sy7758 *sydev;
+	unsigned int dev_id;
+	int ret;
+
+	sydev = devm_kzalloc(dev, sizeof(*sydev), GFP_KERNEL);
+	if (!sydev)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, sydev);
+
+	/* Initialize regmap */
+	sydev->client = client;
+	sydev->regmap = devm_regmap_init_i2c(client, &sy7758_regmap_config);
+	if (IS_ERR(sydev->regmap))
+		return dev_err_probe(dev, PTR_ERR(sydev->regmap),
+				     "failed to init regmap\n");
+
+	/* Get and enable regulators */
+	ret = devm_regulator_get_enable(dev, "vddio");
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get regulator\n");
+
+	usleep_range(100, 200);
+
+	/* Get enable GPIO and set to high */
+	sydev->gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_HIGH);
+	if (IS_ERR(sydev->gpio))
+		return dev_err_probe(dev, PTR_ERR(sydev->gpio),
+				     "failed to get enable GPIO\n");
+
+	/* Let some time for HW to settle */
+	usleep_range(10000, 11000);
+
+	/* try read and check device id */
+	ret = regmap_read(sydev->regmap, REG_DEV_ID, &dev_id);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "failed to read device id\n");
+	if (dev_id != 0x63) {
+		dev_err(dev, "unexpected device id: 0x%02x\n", dev_id);
+		return -ENODEV;
+	}
+
+	/* Initialize and set default brightness */
+	ret = sy7758_init(sydev);
+	if (ret)
+		return ret;
+
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = MAX_BRIGHTNESS;
+	props.brightness = DEFAULT_BRIGHTNESS;
+	props.scale = BACKLIGHT_SCALE_LINEAR;
+
+	sydev->bl = devm_backlight_device_register(dev, "sy7758-backlight",
+						   dev, sydev, &sy7758_backlight_ops,
+						   &props);
+	if (IS_ERR(sydev->bl))
+		return dev_err_probe(dev, PTR_ERR(sydev->bl),
+				     "failed to register backlight device\n");
+
+	return backlight_update_status(sydev->bl);
+}
+
+static void sy7758_remove(struct i2c_client *client)
+{
+	struct sy7758 *sydev = i2c_get_clientdata(client);
+
+	backlight_disable(sydev->bl);
+}
+
+static const struct i2c_device_id sy7758_ids[] = {
+	{ "sy7758" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sy7758_ids);
+
+static const struct of_device_id sy7758_match_table[] = {
+	{ .compatible = "silergy,sy7758", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, sy7758_match_table);
+
+static struct i2c_driver sy7758_driver = {
+	.driver = {
+		.name = "sy7758",
+		.of_match_table = sy7758_match_table,
+	},
+	.probe = sy7758_probe,
+	.remove = sy7758_remove,
+	.id_table = sy7758_ids,
+};
+
+module_i2c_driver(sy7758_driver);
+
+MODULE_DESCRIPTION("Silergy SY7758 Backlight Driver");
+MODULE_AUTHOR("Kancy Joe <kancy2333@outlook.com>");
+MODULE_LICENSE("GPL");

-- 
2.34.1

Re: [PATCH v2 2/2] backlight: Add SY7758 6-channel High Efficiency LED Driver support

[Daniel Thompson]

On Thu, Apr 30, 2026 at 11:47:16AM +0200, Neil Armstrong wrote:
> From: KancyJoe <kancy2333@outlook.com>
>
> Implement support for the Silergy SY7758 6-channel High Efficiency LED
> Driver used for backlight brightness control in the Ayaneo Pocket S2
> dual-DSI panel.
>
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> Signed-off-by: KancyJoe <kancy2333@outlook.com>
> ---
>  drivers/video/backlight/Kconfig  |   8 +
>  drivers/video/backlight/Makefile |   1 +
>  drivers/video/backlight/sy7758.c | 311 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 320 insertions(+)
> <snip>
> diff --git a/drivers/video/backlight/sy7758.c b/drivers/video/backlight/sy7758.c
> new file mode 100644
> index 000000000000..9b2d3bbb4ded
> --- /dev/null
> +++ b/drivers/video/backlight/sy7758.c
> @@ -0,0 +1,311 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Silergy SY7758 6-channel High Efficiency LED Driver
> + *
> + * Copyright (C) 2025 Kancy Joe <kancy2333@outlook.com>
> + * Copyright (C) 2026 Linaro Limited
> + * Author: Neil Armstrong <neil.armstrong@linaro.org>

I'm a bit confused by this comment. The git author and the
MODULE_AUTHOR() is Kancy Joe. What does this comment signify?


> + */
> <snip>
> +/* OTP memory */
> +#define REG_OTP_CFG98 0x98
> +#define REG_OTP_CFG9E 0x9E
> +#define REG_OTP_CFG0 0xA0
> +#define REG_OTP_CFG1 0xA1
> +#define REG_OTP_CFG2 0xA2
> +#define REG_OTP_CFG3 0xA3
> +#define REG_OTP_CFG4 0xA4
> +#define REG_OTP_CFG5 0xA5
> +#define REG_OTP_CFG6 0xA6
> +#define REG_OTP_CFG7 0xA7
> +#define REG_OTP_CFG9 0xA9
> +#define REG_OTP_CFGA 0xAA
> +#define REG_OTP_CFGE 0xAE

There seems to be a lot of unused macros here, especially
combined with the unused bitfields that tell us how to interpret
the values.

Do we need them?


> <snip>
> +static int sy7758_probe(struct i2c_client *client)
> +{
> +	struct backlight_properties props = { };
> +	struct device *dev = &client->dev;
> +	struct sy7758 *sydev;
> +	unsigned int dev_id;
> +	int ret;
> +
> +	sydev = devm_kzalloc(dev, sizeof(*sydev), GFP_KERNEL);
> +	if (!sydev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, sydev);
> +
> +	/* Initialize regmap */
> +	sydev->client = client;
> +	sydev->regmap = devm_regmap_init_i2c(client, &sy7758_regmap_config);
> +	if (IS_ERR(sydev->regmap))
> +		return dev_err_probe(dev, PTR_ERR(sydev->regmap),
> +				     "failed to init regmap\n");
> +
> +	/* Get and enable regulators */
> +	ret = devm_regulator_get_enable(dev, "vddio");
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to get regulator\n");
> +
> +	usleep_range(100, 200);

Any reason not to use fsleep() here?


> +	/* Get enable GPIO and set to high */
> +	sydev->gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_HIGH);
> +	if (IS_ERR(sydev->gpio))
> +		return dev_err_probe(dev, PTR_ERR(sydev->gpio),
> +				     "failed to get enable GPIO\n");
> +
> +	/* Let some time for HW to settle */
> +	usleep_range(10000, 11000);

And here?


> +
> +	/* try read and check device id */
> +	ret = regmap_read(sydev->regmap, REG_DEV_ID, &dev_id);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "failed to read device id\n");
> +	if (dev_id != 0x63) {
> +		dev_err(dev, "unexpected device id: 0x%02x\n", dev_id);
> +		return -ENODEV;
> +	}
> +
> +	/* Initialize and set default brightness */
> +	ret = sy7758_init(sydev);
> +	if (ret)
> +		return ret;
> +
> +	props.type = BACKLIGHT_RAW;
> +	props.max_brightness = MAX_BRIGHTNESS;
> +	props.brightness = DEFAULT_BRIGHTNESS;
> +	props.scale = BACKLIGHT_SCALE_LINEAR;
> +
> +	sydev->bl = devm_backlight_device_register(dev, "sy7758-backlight",
> +						   dev, sydev, &sy7758_backlight_ops,
> +						   &props);
> +	if (IS_ERR(sydev->bl))
> +		return dev_err_probe(dev, PTR_ERR(sydev->bl),
> +				     "failed to register backlight device\n");
> +
> +	return backlight_update_status(sydev->bl);
> +}


Daniel.

Re: [PATCH v2 2/2] backlight: Add SY7758 6-channel High Efficiency LED Driver support

[Neil Armstrong]

Hi,

On 5/15/26 18:28, Daniel Thompson wrote:
> On Thu, Apr 30, 2026 at 11:47:16AM +0200, Neil Armstrong wrote:
>> From: KancyJoe <kancy2333@outlook.com>
>>
>> Implement support for the Silergy SY7758 6-channel High Efficiency LED
>> Driver used for backlight brightness control in the Ayaneo Pocket S2
>> dual-DSI panel.
>>
>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>> Signed-off-by: KancyJoe <kancy2333@outlook.com>
>> ---
>>   drivers/video/backlight/Kconfig  |   8 +
>>   drivers/video/backlight/Makefile |   1 +
>>   drivers/video/backlight/sy7758.c | 311 +++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 320 insertions(+)
>> <snip>
>> diff --git a/drivers/video/backlight/sy7758.c b/drivers/video/backlight/sy7758.c
>> new file mode 100644
>> index 000000000000..9b2d3bbb4ded
>> --- /dev/null
>> +++ b/drivers/video/backlight/sy7758.c
>> @@ -0,0 +1,311 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Silergy SY7758 6-channel High Efficiency LED Driver
>> + *
>> + * Copyright (C) 2025 Kancy Joe <kancy2333@outlook.com>
>> + * Copyright (C) 2026 Linaro Limited
>> + * Author: Neil Armstrong <neil.armstrong@linaro.org>
> 
> I'm a bit confused by this comment. The git author and the
> MODULE_AUTHOR() is Kancy Joe. What does this comment signify?

I'll fix this in v3

> 
> 
>> + */
>> <snip>
>> +/* OTP memory */
>> +#define REG_OTP_CFG98 0x98
>> +#define REG_OTP_CFG9E 0x9E
>> +#define REG_OTP_CFG0 0xA0
>> +#define REG_OTP_CFG1 0xA1
>> +#define REG_OTP_CFG2 0xA2
>> +#define REG_OTP_CFG3 0xA3
>> +#define REG_OTP_CFG4 0xA4
>> +#define REG_OTP_CFG5 0xA5
>> +#define REG_OTP_CFG6 0xA6
>> +#define REG_OTP_CFG7 0xA7
>> +#define REG_OTP_CFG9 0xA9
>> +#define REG_OTP_CFGA 0xAA
>> +#define REG_OTP_CFGE 0xAE
> 
> There seems to be a lot of unused macros here, especially
> combined with the unused bitfields that tell us how to interpret
> the values.
> 
> Do we need them?

I'll drop those

> 
> 
>> <snip>
>> +static int sy7758_probe(struct i2c_client *client)
>> +{
>> +	struct backlight_properties props = { };
>> +	struct device *dev = &client->dev;
>> +	struct sy7758 *sydev;
>> +	unsigned int dev_id;
>> +	int ret;
>> +
>> +	sydev = devm_kzalloc(dev, sizeof(*sydev), GFP_KERNEL);
>> +	if (!sydev)
>> +		return -ENOMEM;
>> +
>> +	i2c_set_clientdata(client, sydev);
>> +
>> +	/* Initialize regmap */
>> +	sydev->client = client;
>> +	sydev->regmap = devm_regmap_init_i2c(client, &sy7758_regmap_config);
>> +	if (IS_ERR(sydev->regmap))
>> +		return dev_err_probe(dev, PTR_ERR(sydev->regmap),
>> +				     "failed to init regmap\n");
>> +
>> +	/* Get and enable regulators */
>> +	ret = devm_regulator_get_enable(dev, "vddio");
>> +	if (ret)
>> +		return dev_err_probe(dev, ret, "failed to get regulator\n");
>> +
>> +	usleep_range(100, 200);
> 
> Any reason not to use fsleep() here?

Thanks, I'll switch to fsleep

> 
> 
>> +	/* Get enable GPIO and set to high */
>> +	sydev->gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_HIGH);
>> +	if (IS_ERR(sydev->gpio))
>> +		return dev_err_probe(dev, PTR_ERR(sydev->gpio),
>> +				     "failed to get enable GPIO\n");
>> +
>> +	/* Let some time for HW to settle */
>> +	usleep_range(10000, 11000);
> 
> And here?
> 
> 
>> +
>> +	/* try read and check device id */
>> +	ret = regmap_read(sydev->regmap, REG_DEV_ID, &dev_id);
>> +	if (ret < 0)
>> +		return dev_err_probe(dev, ret, "failed to read device id\n");
>> +	if (dev_id != 0x63) {
>> +		dev_err(dev, "unexpected device id: 0x%02x\n", dev_id);
>> +		return -ENODEV;
>> +	}
>> +
>> +	/* Initialize and set default brightness */
>> +	ret = sy7758_init(sydev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	props.type = BACKLIGHT_RAW;
>> +	props.max_brightness = MAX_BRIGHTNESS;
>> +	props.brightness = DEFAULT_BRIGHTNESS;
>> +	props.scale = BACKLIGHT_SCALE_LINEAR;
>> +
>> +	sydev->bl = devm_backlight_device_register(dev, "sy7758-backlight",
>> +						   dev, sydev, &sy7758_backlight_ops,
>> +						   &props);
>> +	if (IS_ERR(sydev->bl))
>> +		return dev_err_probe(dev, PTR_ERR(sydev->bl),
>> +				     "failed to register backlight device\n");
>> +
>> +	return backlight_update_status(sydev->bl);
>> +}
> 
> 
> Daniel.

Thanks,
Neil