Re: [PATCH v1 1/2] leds: rt4505: Add support for Richtek RT4505 flash led controller

Jacek Anaszewski
2020-10-27T16:41:12Z

Hi Pavel, ChiYuan,

On 10/27/20 9:29 AM, Pavel Machek wrote:
> Hi!
>
>> From: ChiYuan Huang <cy_huang@richtek.com>
>>
>> Add support for RT4505 flash led controller. It can support up to 1.5A
>> flash current with hardware timeout and low input voltage
>> protection.
>
> Please use upper-case "LED" everywhere.
>
> This should be 2nd in the series, after DT changes.
>
>> Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
>> ---
>> drivers/leds/Kconfig | 11 ++
>> drivers/leds/Makefile | 1 +
>> drivers/leds/leds-rt4505.c | 397 +++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 409 insertions(+)
>> create mode 100644 drivers/leds/leds-rt4505.c
[...]
>> +static int rt4505_torch_brightness_set(struct led_classdev *lcdev, enum led_brightness level)
>> +{
>
> 80 columns, where easy.
>
>> + struct rt4505_priv *priv = container_of(lcdev, struct rt4505_priv, flash.led_cdev);
>> + u32 val = 0;
>> + int ret;
>> +
>> + mutex_lock(&priv->lock);
>> +
>> + if (level != LED_OFF) {
>> + ret = regmap_update_bits(priv->regmap, RT4505_REG_ILED, RT4505_ITORCH_MASK,
>> + (level - 1) << RT4505_ITORCH_SHIFT);
>> + if (ret)
>> + goto unlock;
>> +
>> + val = RT4505_TORCH_SET;
>> + }
>> +
>> + ret = regmap_update_bits(priv->regmap, RT4505_REG_ENABLE, RT4505_ENABLE_MASK, val);
>> +
>> +unlock:
>> + mutex_unlock(&priv->lock);
>> + return ret;
>> +}
>
> Why is the locking needed? What will the /sys/class/leds interface
> look like on system with your flash?

The locking is needed since this can be called via led_set_brightness()
from any place in the kernel, and especially from triggers.

--
Best regards,
Jacek Anaszewski