linux-kernel - Re: [PATCH v2 3/3] arch/powerpc: Remove <linux/fb.h> from backlight code

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Message-ID: <15e13364-8b43-402c-836b-436499906b74@csgroup.eu>
Date: Tue, 5 Mar 2024 09:25:54 +0000
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Thomas Zimmermann <tzimmermann@...e.de>, "mpe@...erman.id.au"
	<mpe@...erman.id.au>, "jani.nikula@...el.com" <jani.nikula@...el.com>,
	"naresh.kamboju@...aro.org" <naresh.kamboju@...aro.org>, "deller@....de"
	<deller@....de>, "npiggin@...il.com" <npiggin@...il.com>,
	"aneesh.kumar@...nel.org" <aneesh.kumar@...nel.org>,
	"naveen.n.rao@...ux.ibm.com" <naveen.n.rao@...ux.ibm.com>
CC: "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	"lkft-triage@...ts.linaro.org" <lkft-triage@...ts.linaro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v2 3/3] arch/powerpc: Remove <linux/fb.h> from backlight
 code



Le 05/03/2024 à 10:01, Thomas Zimmermann a écrit :
> Replace <linux/fb.h> with a forward declaration in <asm/backlight.h> to
> resolves an unnecessary dependency. Remove pmac_backlight_curve_lookup()
> and struct fb_info from source and header files. The function and the
> framebuffer struct is unused. No functional changes.

When you remove pmac_backlight_curve_lookup() prototype you'll then get 
a warning/error about missing prototype when building 
arch/powerpc/platforms/powermac/backlight.c

The fonction is not used outside of that file so it should be static. 
And then it is not used in that file either so it should be removed 
completely. Indeed last use of that function was removed by commit 
d565dd3b0824 ("[PATCH] powerpc: More via-pmu backlight fixes") so the 
function can safely be removed.

Christophe

> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
> ---
>   arch/powerpc/include/asm/backlight.h        |  5 ++--
>   arch/powerpc/platforms/powermac/backlight.c | 26 ---------------------
>   2 files changed, 2 insertions(+), 29 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/backlight.h b/arch/powerpc/include/asm/backlight.h
> index 1b5eab62ed047..061a910d74929 100644
> --- a/arch/powerpc/include/asm/backlight.h
> +++ b/arch/powerpc/include/asm/backlight.h
> @@ -10,15 +10,14 @@
>   #define __ASM_POWERPC_BACKLIGHT_H
>   #ifdef __KERNEL__
>   
> -#include <linux/fb.h>
>   #include <linux/mutex.h>
>   
> +struct backlight_device;
> +
>   /* For locking instructions, see the implementation file */
>   extern struct backlight_device *pmac_backlight;
>   extern struct mutex pmac_backlight_mutex;
>   
> -extern int pmac_backlight_curve_lookup(struct fb_info *info, int value);
> -
>   extern int pmac_has_backlight_type(const char *type);
>   
>   extern void pmac_backlight_key(int direction);
> diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
> index aeb79a8b3e109..12bc01353bd3c 100644
> --- a/arch/powerpc/platforms/powermac/backlight.c
> +++ b/arch/powerpc/platforms/powermac/backlight.c
> @@ -9,7 +9,6 @@
>    */
>   
>   #include <linux/kernel.h>
> -#include <linux/fb.h>
>   #include <linux/backlight.h>
>   #include <linux/adb.h>
>   #include <linux/pmu.h>
> @@ -72,31 +71,6 @@ int pmac_has_backlight_type(const char *type)
>   	return 0;
>   }
>   
> -int pmac_backlight_curve_lookup(struct fb_info *info, int value)
> -{
> -	int level = (FB_BACKLIGHT_LEVELS - 1);
> -
> -	if (info && info->bl_dev) {
> -		int i, max = 0;
> -
> -		/* Look for biggest value */
> -		for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
> -			max = max((int)info->bl_curve[i], max);
> -
> -		/* Look for nearest value */
> -		for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
> -			int diff = abs(info->bl_curve[i] - value);
> -			if (diff < max) {
> -				max = diff;
> -				level = i;
> -			}
> -		}
> -
> -	}
> -
> -	return level;
> -}
> -
>   static void pmac_backlight_key_worker(struct work_struct *work)
>   {
>   	if (atomic_read(&kernel_backlight_disabled))