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

[Claude Code Review Bot <claude-review@example.com>]

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.

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Generated by Claude Code Patch Reviewer