[v1] leds: group-multicolor: Add support for initial value.

[PATCH] leds: group-multicolor: Add support for initial value.

Posted by Martijn de Gouw 2 months, 4 weeks ago

It's possible to set a default state for leds in the dts with
'default-state', but this was not reflected when the LEDs are grouped.
This patch adds support for keeping the default-state value.

Signed-off-by: Martijn de Gouw <martijn.de.gouw@prodrive-technologies.com>
---
 drivers/leds/rgb/leds-group-multicolor.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/rgb/leds-group-multicolor.c b/drivers/leds/rgb/leds-group-multicolor.c
index 548c7dd63ba1e..b3e46a51dfbc7 100644
--- a/drivers/leds/rgb/leds-group-multicolor.c
+++ b/drivers/leds/rgb/leds-group-multicolor.c
@@ -69,6 +69,7 @@ static int leds_gmc_probe(struct platform_device *pdev)
 	struct mc_subled *subled;
 	struct leds_multicolor *priv;
 	unsigned int max_brightness = 0;
+	unsigned int default_brightness = 0;
 	int i, ret, count = 0, common_flags = 0;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
@@ -96,6 +97,12 @@ static int leds_gmc_probe(struct platform_device *pdev)
 
 		max_brightness = max(max_brightness, led_cdev->max_brightness);
 
+		/* If any LED is on, set brightness to the max brightness.
+		 * The actual brightness of the LED is set as intensity value.
+		 */
+		if (led_cdev->brightness)
+			default_brightness = max_brightness;
+
 		count++;
 	}
 
@@ -109,14 +116,16 @@ static int leds_gmc_probe(struct platform_device *pdev)
 
 		subled[i].color_index = led_cdev->color;
 
-		/* Configure the LED intensity to its maximum */
-		subled[i].intensity = max_brightness;
+		/* Configure the LED intensity to its current brightness */
+		subled[i].intensity = DIV_ROUND_CLOSEST(led_cdev->brightness * max_brightness,
+							led_cdev->max_brightness);
 	}
 
 	/* Initialise the multicolor's LED class device */
 	cdev = &priv->mc_cdev.led_cdev;
 	cdev->brightness_set_blocking = leds_gmc_set;
 	cdev->max_brightness = max_brightness;
+	cdev->brightness = default_brightness;
 	cdev->color = LED_COLOR_ID_MULTI;
 	priv->mc_cdev.num_colors = count;
 
-- 
2.39.2

Re: [PATCH] leds: group-multicolor: Add support for initial value.

Posted by Lee Jones 2 months, 2 weeks ago

On Tue, 11 Nov 2025, Martijn de Gouw wrote:

> It's possible to set a default state for leds in the dts with
> 'default-state', but this was not reflected when the LEDs are grouped.
> This patch adds support for keeping the default-state value.
> 
> Signed-off-by: Martijn de Gouw <martijn.de.gouw@prodrive-technologies.com>
> ---
>  drivers/leds/rgb/leds-group-multicolor.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/leds/rgb/leds-group-multicolor.c b/drivers/leds/rgb/leds-group-multicolor.c
> index 548c7dd63ba1e..b3e46a51dfbc7 100644
> --- a/drivers/leds/rgb/leds-group-multicolor.c
> +++ b/drivers/leds/rgb/leds-group-multicolor.c
> @@ -69,6 +69,7 @@ static int leds_gmc_probe(struct platform_device *pdev)
>  	struct mc_subled *subled;
>  	struct leds_multicolor *priv;
>  	unsigned int max_brightness = 0;
> +	unsigned int default_brightness = 0;
>  	int i, ret, count = 0, common_flags = 0;
>  
>  	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> @@ -96,6 +97,12 @@ static int leds_gmc_probe(struct platform_device *pdev)
>  
>  		max_brightness = max(max_brightness, led_cdev->max_brightness);
>  
> +		/* If any LED is on, set brightness to the max brightness.
> +		 * The actual brightness of the LED is set as intensity value.
> +		 */

I don't know this code well, but if no one complains, I can take your
word for this.

However, the comment needs changing to proper multi-line format.

        /*
         * This is the preferred style for multi-line
         * comments in the Linux kernel source code.
         * Please use it consistently.
         *
         * Description:  A column of asterisks on the left side,
         * with beginning and ending almost-blank lines.
         */

> +		if (led_cdev->brightness)
> +			default_brightness = max_brightness;
> +
>  		count++;
>  	}
>  
> @@ -109,14 +116,16 @@ static int leds_gmc_probe(struct platform_device *pdev)
>  
>  		subled[i].color_index = led_cdev->color;
>  
> -		/* Configure the LED intensity to its maximum */
> -		subled[i].intensity = max_brightness;
> +		/* Configure the LED intensity to its current brightness */
> +		subled[i].intensity = DIV_ROUND_CLOSEST(led_cdev->brightness * max_brightness,

How does this work?  Won't this value be huge?

> +							led_cdev->max_brightness);

Also we said we were going to set actual brightness with the intensity
in the comment above, but we appear to be using max_brightness again?

>  	}
>  
>  	/* Initialise the multicolor's LED class device */
>  	cdev = &priv->mc_cdev.led_cdev;
>  	cdev->brightness_set_blocking = leds_gmc_set;
>  	cdev->max_brightness = max_brightness;
> +	cdev->brightness = default_brightness;
>  	cdev->color = LED_COLOR_ID_MULTI;
>  	priv->mc_cdev.num_colors = count;
>  
> -- 
> 2.39.2
> 

-- 
Lee Jones [李琼斯]

Re: [PATCH] leds: group-multicolor: Add support for initial value.

Posted by Martijn de Gouw 2 months, 2 weeks ago

Hi,

On 11/19/2025 5:51 PM, Lee Jones wrote:
> On Tue, 11 Nov 2025, Martijn de Gouw wrote:
> 
>> It's possible to set a default state for leds in the dts with
>> 'default-state', but this was not reflected when the LEDs are grouped.
>> This patch adds support for keeping the default-state value.
>>
>> Signed-off-by: Martijn de Gouw <martijn.de.gouw@prodrive-technologies.com>
>> ---
>>  drivers/leds/rgb/leds-group-multicolor.c | 13 +++++++++++--
>>  1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/leds/rgb/leds-group-multicolor.c b/drivers/leds/rgb/leds-group-multicolor.c
>> index 548c7dd63ba1e..b3e46a51dfbc7 100644
>> --- a/drivers/leds/rgb/leds-group-multicolor.c
>> +++ b/drivers/leds/rgb/leds-group-multicolor.c
>> @@ -69,6 +69,7 @@ static int leds_gmc_probe(struct platform_device *pdev)
>>  	struct mc_subled *subled;
>>  	struct leds_multicolor *priv;
>>  	unsigned int max_brightness = 0;
>> +	unsigned int default_brightness = 0;
>>  	int i, ret, count = 0, common_flags = 0;
>>  
>>  	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> @@ -96,6 +97,12 @@ static int leds_gmc_probe(struct platform_device *pdev)
>>  
>>  		max_brightness = max(max_brightness, led_cdev->max_brightness);
>>  
>> +		/* If any LED is on, set brightness to the max brightness.
>> +		 * The actual brightness of the LED is set as intensity value.
>> +		 */
> 
> I don't know this code well, but if no one complains, I can take your
> word for this.
> 
> However, the comment needs changing to proper multi-line format.
> 
>         /*
>          * This is the preferred style for multi-line
>          * comments in the Linux kernel source code.
>          * Please use it consistently.
>          *
>          * Description:  A column of asterisks on the left side,
>          * with beginning and ending almost-blank lines.
>          */

Will do!

> 
>> +		if (led_cdev->brightness)
>> +			default_brightness = max_brightness;
>> +
>>  		count++;
>>  	}
>>  
>> @@ -109,14 +116,16 @@ static int leds_gmc_probe(struct platform_device *pdev)
>>  
>>  		subled[i].color_index = led_cdev->color;
>>  
>> -		/* Configure the LED intensity to its maximum */
>> -		subled[i].intensity = max_brightness;
>> +		/* Configure the LED intensity to its current brightness */
>> +		subled[i].intensity = DIV_ROUND_CLOSEST(led_cdev->brightness * max_brightness,
> 
> How does this work?  Won't this value be huge?

It calculates the intensity of the led with respect to the max_brightness of the whole group.
So actually it's doing:
subled[i].intensity = group->max_brightness * (led_cdev->brightness/led_cdev->max_brightness).

I highest value I could find for a max_brightness is 4096 (12 bit). Maybe some PWM LEDs use up to 16bit?
So I made the assumption that is should not be an issue.
I wrote it this way, where the multiplication comes first, because integer divisions don't work well.
> 
>> +							led_cdev->max_brightness);
> 
> Also we said we were going to set actual brightness with the intensity
> in the comment above, but we appear to be using max_brightness again?

I'll try to clarify the comments.

> 
>>  	}
>>  
>>  	/* Initialise the multicolor's LED class device */
>>  	cdev = &priv->mc_cdev.led_cdev;
>>  	cdev->brightness_set_blocking = leds_gmc_set;
>>  	cdev->max_brightness = max_brightness;
>> +	cdev->brightness = default_brightness;
>>  	cdev->color = LED_COLOR_ID_MULTI;
>>  	priv->mc_cdev.num_colors = count;
>>  
>> -- 
>> 2.39.2
>>
> 

-- 
Martijn de Gouw
Designer
Prodrive Technologies B.V.
Mobile: +31 63 17 76 161
Phone:  +31 40 26 76 200