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

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Message-ID: <f10f4f22-0bec-4c0c-8b0f-3f68227dc9d0@csgroup.eu>
Date: Tue, 5 Mar 2024 10:06:29 +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 11:04, Thomas Zimmermann a écrit :
> Hi
> 
> Am 05.03.24 um 10:25 schrieb Christophe Leroy:
>>
>> 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.
> 
> Isn't that what my patch is doing? I have no callers of the function in 
> my tree (drm-tip), so I removed it entirely. Should I add a Fixes tag 
> against commit d565dd3b0824? Best regards Thomas

Sorry I overlooked your patch and focussed on the removal of the 
prototype and missed the removal of the function.

Christophe

>>
>> 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))
>