linux-kernel - Re: [PATCH v2] leds: gpio: Set max brightness to 1

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Date:   Tue, 29 Dec 2020 19:09:11 +0100
From:   Dylan Van Assche <me@...anvanassche.be>
To:     Pavel Machek <pavel@....cz>
Cc:     dmurphy@...com, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] leds: gpio: Set max brightness to 1

Hi!

Thanks for the feedback!
Indeed, this can be even more simplified with your suggestion.
I will send a new version of the patch soon.

Happy holidays!

Kind regards,
Dylan Van Assche

On Tue, 2020-12-29 at 17:04 +0100, Pavel Machek wrote:
> Hi!
> 
> > GPIO LEDs only know 2 states: ON or OFF and do not have PWM
> > capabilities.
> > However, the max brightness is reported as 255.
> > 
> > This patch sets the max brightness value of a GPIO controlled LED
> > to 1.
> > 
> > Tested on my PinePhone 1.2.
> > 
> > Signed-off-by: Dylan Van Assche <me@...anvanassche.be>
> > ---
> > v2 drops an obsolete change in include/linux/leds.h
> 
> I thought that one looked odd.
> 
> > +++ b/drivers/leds/leds-gpio.c
> > @@ -96,7 +96,8 @@ static int create_gpio_led(const struct gpio_led
> > *template,
> >  	} else {
> >  		state = (template->default_state ==
> > LEDS_GPIO_DEFSTATE_ON);
> >  	}
> > -	led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
> > +	led_dat->cdev.brightness = state ? LED_ON : LED_OFF;
> > +	led_dat->cdev.max_brightness = LED_ON;
> 
> Would simpler version work:
> 
> > +	led_dat->cdev.brightness = state;
> > +	led_dat->cdev.max_brightness = 1;
> 
> ? Easier to understand... I'd prefer that version unless it causes
> warnings or something.
> 
> 								Pavel