linux-kernel - Re: [PATCH 2/2] leds: pwm: Add optional DT property default-brightness

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Message-ID: <20241031143250.GH10824@google.com>
Date: Thu, 31 Oct 2024 14:32:50 +0000
From: Lee Jones <lee@...nel.org>
To: George Stark <gnstark@...utedevices.com>
Cc: pavel@....cz, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
	linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel@...utedevices.com
Subject: Re: [PATCH 2/2] leds: pwm: Add optional DT property
 default-brightness

On Tue, 15 Oct 2024, George Stark wrote:

> When probing if default LED state is on then default brightness will be
> applied instead of max brightness.
> 
> Signed-off-by: George Stark <gnstark@...utedevices.com>
> ---
>  drivers/leds/leds-pwm.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
> index 7961dca0db2f..514fc8ca3e80 100644
> --- a/drivers/leds/leds-pwm.c
> +++ b/drivers/leds/leds-pwm.c
> @@ -65,7 +65,8 @@ static int led_pwm_set(struct led_classdev *led_cdev,
>  
>  __attribute__((nonnull))
>  static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
> -		       struct led_pwm *led, struct fwnode_handle *fwnode)
> +		       struct led_pwm *led, struct fwnode_handle *fwnode,
> +		       unsigned int default_brightness)
>  {
>  	struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
>  	struct led_init_data init_data = { .fwnode = fwnode };
> @@ -104,7 +105,7 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
>  	/* set brightness */
>  	switch (led->default_state) {
>  	case LEDS_DEFSTATE_ON:
> -		led_data->cdev.brightness = led->max_brightness;
> +		led_data->cdev.brightness = default_brightness;
>  		break;
>  	case LEDS_DEFSTATE_KEEP:
>  		{
> @@ -141,6 +142,7 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
>  static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
>  {
>  	struct led_pwm led;
> +	unsigned int default_brightness;
>  	int ret;
>  
>  	device_for_each_child_node_scoped(dev, fwnode) {
> @@ -160,7 +162,12 @@ static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
>  
>  		led.default_state = led_init_default_state_get(fwnode);
>  
> -		ret = led_pwm_add(dev, priv, &led, fwnode);
> +		ret = fwnode_property_read_u32(fwnode, "default-brightness",
> +					       &default_brightness);
> +		if (ret < 0 || default_brightness > led.max_brightness)
> +			default_brightness = led.max_brightness;
> +
> +		ret = led_pwm_add(dev, priv, &led, fwnode, default_brightness);

This creates a lot more hopping around than is necessary.

Since led_pwm_add() already has access to the fwnode, why not look up
the property in there instead, thus massively simplifying things.


>  		if (ret)
>  			return ret;
>  	}
> -- 
> 2.25.1
> 

-- 
Lee Jones [李琼斯]