[PATCH v4 0/2] backlight: Add SY7758 6-channel High Efficiency LED Driver support

[PATCH v4 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 v4:
- Fixed Kconfig typo
- Remove again unused macros
- Added delay.h include
- Link to v3: https://patch.msgid.link/20260519-topic-sm8650-ayaneo-pocket-s2-sy7758-v3-0-ec8194bbc885@linaro.org

Changes in v3:
- Dropped unused macros
- Added second autho entry to match header and commit message
- Move my signof at the end
- Switched to flseep()
- Link to v2: https://patch.msgid.link/20260430-topic-sm8650-ayaneo-pocket-s2-sy7758-v2-0-308140640de9@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                   | 259 +++++++++++++++++++++
 4 files changed, 321 insertions(+)
---
base-commit: 39704f00f747aba3144289870b5fd8ac230a9aaf
change-id: 20260428-topic-sm8650-ayaneo-pocket-s2-sy7758-3081ee7f1e25

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

[PATCH v4 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

[PATCH v4 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: KancyJoe <kancy2333@outlook.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 drivers/video/backlight/Kconfig  |   8 ++
 drivers/video/backlight/Makefile |   1 +
 drivers/video/backlight/sy7758.c | 259 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 268 insertions(+)

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index a7a3fbaf7c29..a1f70a2bae99 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 Pocket 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..198d55939438
--- /dev/null
+++ b/drivers/video/backlight/sy7758.c
@@ -0,0 +1,259 @@
+// 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/delay.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_DEV_CTL		0x01
+#define REG_DEV_ID		0x03
+#define REG_BRT_12BIT_L		0x10
+#define REG_BRT_12BIT_H		0x11
+
+/* OTP memory */
+#define REG_OTP_CFG0		0xA0
+#define REG_OTP_CFG1		0xA1
+#define REG_OTP_CFG2		0xA2
+#define REG_OTP_CFG5		0xA5
+#define REG_OTP_CFG9		0xA9
+
+/* 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 MSK_BRT_12BIT_L		GENMASK(7, 0)
+#define MSK_BRT_12BIT_H		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 BIT_CFG5_PWM_DIRECT	BIT(7)
+#define MSK_CFG5_PS_MODE	GENMASK(6, 4)
+#define MSK_CFG5_PWM_FREQ	GENMASK(3, 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)
+
+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");
+
+	fsleep(100);
+
+	/* 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 */
+	fsleep(10000);
+
+	/* 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_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");
+MODULE_LICENSE("GPL");

-- 
2.34.1

Claude review: backlight: Add SY7758 6-channel High Efficiency LED Driver support

[Claude Code Review Bot]

Overall Series Review

Subject: backlight: Add SY7758 6-channel High Efficiency LED Driver support
Author: Neil Armstrong <neil.armstrong@linaro.org>
Patches: 3
Reviewed: 2026-05-25T20:43:17.434215

---

This is a v4 series adding a new backlight driver for the Silergy SY7758 6-channel LED driver, used in the Ayaneo Pocket S2. The series consists of a DT binding (patch 1) and the driver itself (patch 2). The code is clean, well-structured, and follows established kernel backlight driver patterns (closely resembling ktz8866.c). The driver uses devm-managed resources properly and has good error handling throughout.

The main issues are minor: a Makefile alphabetical ordering mistake, some redundant `FIELD_PREP` usage on fields already at bit 0, and hardcoded hardware configuration values that could benefit from DT properties in the future.

**Verdict: Looks good overall with minor nits.**

---

---
Generated by Claude Code Patch Reviewer

Claude review: dt-bindings: leds: backlight: document the SY7758 6-channel High Efficiency LED Driver

[Claude Code Review Bot]

Patch Review

This patch adds the YAML devicetree binding for the SY7758. It's straightforward and already carries a `Reviewed-by` from Krzysztof Kozlowski.

The binding correctly references `common.yaml#`, defines the required properties (`compatible`, `reg`, `vddio-supply`, `enable-gpios`), and uses `unevaluatedProperties: false`. The example is well-formed and includes the necessary `#include` for `GPIO_ACTIVE_HIGH`.

**No issues found.** This patch is clean.

---

---
Generated by Claude Code Patch Reviewer

Claude review: backlight: Add SY7758 6-channel High Efficiency LED Driver support

[Claude Code Review Bot]

Patch Review

**Makefile ordering (minor):** The new entry is placed between `SAHARA` and `SKY81452`, but alphabetically `SY7758` sorts after `SKY81452`:

```c
 obj-$(CONFIG_BACKLIGHT_SAHARA)		+= kb3886_bl.o
+obj-$(CONFIG_BACKLIGHT_SY7758)		+= sy7758.o
 obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
```

Should be:

```
 obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
+obj-$(CONFIG_BACKLIGHT_SY7758)		+= sy7758.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
```

**Kconfig ordering (minor):** The entry is placed between `KTZ8866` (K) and `LM3533` (L), but `SY7758` (S) should sort much later. That said, the existing Kconfig is not strictly alphabetical (e.g. `HP680` appears after `OMAP1`, `APPLE` after `MT6370`), so this is cosmetic at best.

**Redundant `FIELD_PREP` for bit-0 fields (style nit):** `MSK_BRT_12BIT_L` is `GENMASK(7, 0)` and `MSK_BRT_12BIT_H` is `GENMASK(3, 0)`. Since both masks start at bit 0, `FIELD_PREP` is a no-op — it doesn't shift. The explicit `& 0xff` / `& 0xf` masks are also redundant when using `FIELD_PREP`, since it already masks the value:

```c
ret = regmap_write(sydev->regmap, REG_BRT_12BIT_L,
                   FIELD_PREP(MSK_BRT_12BIT_L,
                              brightness & 0xff));
```

Either use `FIELD_PREP` alone (dropping the manual masks) or drop `FIELD_PREP` entirely (just write `brightness & 0xff`). Having both is belt-and-suspenders that adds clutter. The same pattern appears in `sy7758_init` for the default brightness writes.

**Unnecessary initialization (trivial):** In `sy7758_init`:

```c
int ret = 0;
```

`ret` is immediately assigned on the next line, so `= 0` is unnecessary.

**`update_status` return style (trivial):** The trailing `return 0` could be simplified:

```c
ret = regmap_write(sydev->regmap, REG_BRT_12BIT_H,
                   FIELD_PREP(MSK_BRT_12BIT_H,
                              (brightness >> 8) & 0xf));
if (ret)
        return ret;

return 0;
```

Could simply be `return regmap_write(...)` for the last write, or `return ret;` instead of the `if`/`return 0` pair. This matches patterns in other backlight drivers.

**Hardcoded init configuration (observation, not a blocker):** `sy7758_init` writes fixed values to multiple OTP/config registers (current limits, boost voltage, PWM frequency, etc.). These are specific to the Ayaneo Pocket S2. If this chip is used on other boards, these values would need to come from DT properties. Acceptable for now given there is only one user, but worth noting for future extensibility.

**`MAX_BRIGHTNESS = 4080` (question):** The 12-bit register range would support up to 4095 (0xFFF). The chosen max of 4080 (0xFF0) presumably comes from the datasheet — if so, no issue, but it's worth confirming this isn't a typo.

**Everything else looks correct:** Probe sequence handles errors well with consistent `dev_err_probe` usage, devm resource management is clean, the device ID check at probe is good practice, and `sy7758_remove` calling `backlight_disable` before devm teardown is correct.

---
Generated by Claude Code Patch Reviewer