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

[Jacek Anaszewski]

Hi Pavel, ChiYuan,

On 10/27/20 9:29 AM, Pavel Machek wrote:
> Hi!
>
> > From: ChiYuan Huang <cy_huang@xxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxx>
> > ---
> >   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