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

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Message-ID: <20201229160450.GA9564@duo.ucw.cz>
Date:   Tue, 29 Dec 2020 17:04:50 +0100
From:   Pavel Machek <pavel@....cz>
To:     Dylan Van Assche <me@...anvanassche.be>
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!

> 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
-- 
http://www.livejournal.com/~pavelmachek

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