linux-kernel - Re: [PATCH 1/2] swap led_brightness from enum to typedef

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Message-ID: <alpine.DEB.2.22.394.2107190912320.178229@ramsan.of.borg>
Date:   Mon, 19 Jul 2021 09:16:52 +0200 (CEST)
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Amy Parker <apark0006@...dent.cerritos.edu>
cc:     pavel@....cz, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] swap led_brightness from enum to typedef

 	Hi Amy,

On Thu, 15 Jul 2021, Amy Parker wrote:
> This commit changes how led_brightness, declared in header file
> include/linux/leds.h, works throughout the kernel, and updates other
> files in accordance.
>
> The TODO located at drivers/leds/TODO requests:
>
> * Get rid of led_brightness
>
> It is really an integer, as maximum is configurable. Get rid of it, or
> make it into typedef or something.
>
> This patch changes the declaration of led_brightness from an enum to a
> typedef. In order to hold the currently existing enum values, macro
> definitions are provided. Files which use led_brightness are updated to
> conform to the new types.
>
> Signed-off-by: Amy Parker <apark0006@...dent.cerritos.edu>

Thanks for your patch!

> 207 files changed, 437 insertions(+), 438 deletions(-)

This touches a lot of files, so we better get it right.

> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -26,12 +26,11 @@ struct device_node;
>  */
>
> /* This is obsolete/useless. We now support variable maximum brightness. */
> -enum led_brightness {
> -	LED_OFF		= 0,
> -	LED_ON		= 1,
> -	LED_HALF	= 127,
> -	LED_FULL	= 255,
> -};
> +typedef u8 led_brightness;

In general, typedefs are frowned upon in the kernel, but there can be a
good reason to use one.
What if the maximum brightness is larger than 255?
Using "unsigned int" sounds better to me, but let's wait for Pavel...

> +#define LED_OFF 0
> +#define LED_ON 1
> +#define LED_HALF 127
> +#define LED_FULL 255

Gr{oetje,eeting}s,

 						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
 							    -- Linus Torvalds