Re: [RFC PATCH 2/2] leds: flash: Add support for the TI LM3643 dual LED flash driver

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Turning off an LED fails to clear the chip mode bits, causing power drain and breaking flash strobe teardown.
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--- Patch [2]: [RFC PATCH 2/2] leds: flash: Add support for the TI LM3643 dual LED flash driver ---
commit bdf1945ab184ca005c2f401ecd5408571ece1de3
Author: Rillian Grant <rillian.grant@gmail.com>

leds: flash: Add support for the TI LM3643 dual LED flash driver
    
The LM3643 is an I2C dual LED flash driver. Its two high-side current
sources share a synchronous boost converter and each supports torch and
flash modes with programmable current and flash timeout alongside fault
reporting.

> diff --git a/drivers/leds/flash/leds-lm3643.c b/drivers/leds/flash/leds-lm3643.c
> new file mode 100644
> --- /dev/null
> +++ b/drivers/leds/flash/leds-lm3643.c

[ ... ]

> +static int lm3643_torch_set_brightness(struct led_classdev *led_cdev,
> +				       enum led_brightness brightness)
> +{

[ ... ]

> +	if (brightness == 0)
> +		return regmap_update_bits(led->regmap, LM3643_REG_ENABLE,
> +				chan->enable_bit, 0);

[Severity: High]
When brightness is 0, this only clears the channel's enable bit but leaves
the LM3643_MODE_MASK bits intact. If no other LEDs are active, does this
leave the chip in an active power state (Torch or Flash mode) instead of
transitioning to LM3643_MODE_STANDBY, potentially causing continuous battery
drain?

[ ... ]

> +static int lm3643_flash_strobe_set(struct led_classdev_flash *fled_cdev, bool state)
> +{

[ ... ]

> +	if (!state) {
> +		if (mode != LM3643_MODE_FLASH || !(enable_reg & chan->enable_bit))
> +			return 0;
> +
> +		return regmap_update_bits(led->regmap, LM3643_REG_ENABLE,
> +			LM3643_MODE_MASK, LM3643_MODE_STANDBY);
> +	}

[Severity: High]
If the torch brightness was set to 0 during a flash, the channel's enable
bit will have been cleared. During the subsequent teardown call to
lm3643_flash_strobe_set() with state = false, does this early return trigger
because the enable bit is no longer set?

This would fail to restore the mode to LM3643_MODE_STANDBY, permanently
stranding the driver's state machine in Flash mode.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260821083620.68324-1-rillian.grant@gmail.com?part=2