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From: Michael Ellerman <mpe@ellerman.id.au>
To: Christophe Leroy <christophe.leroy@csgroup.eu>, Thomas Zimmermann
 <tzimmermann@suse.de>, Jani Nikula <jani.nikula@intel.com>,
 "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Cc: "linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>, Helge
 Deller <deller@gmx.de>, "linux-kernel@vger.kernel.org"
 <linux-kernel@vger.kernel.org>, "lkft-triage@lists.linaro.org"
 <lkft-triage@lists.linaro.org>, "dri-devel@lists.freedesktop.org"
 <dri-devel@lists.freedesktop.org>, Naresh Kamboju
 <naresh.kamboju@linaro.org>
Subject: Re: [PATCH] powerpc: include linux/backlight.h from asm/backlight.h
In-Reply-To: <e5a0e44d-d2b9-49f0-9a08-fb7d9254266c@csgroup.eu>
References: <CA+G9fYsAk5TbqqxFC2W4oHLGA0CbTHMxbeq8QayFXTU75YiueA@mail.gmail.com>
 <20240304095512.742348-1-jani.nikula@intel.com>
 <eed9bb0f-486f-47f3-b4b5-c07adda4a1c7@suse.de>
 <e5a0e44d-d2b9-49f0-9a08-fb7d9254266c@csgroup.eu>
Date: Tue, 05 Mar 2024 11:36:00 +1100
Message-ID: <87frx5plan.fsf@mail.lhotse>
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Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Le 04/03/2024 =C3=A0 11:32, Thomas Zimmermann a =C3=A9crit=C2=A0:
>> Hi
>>=20
>> Am 04.03.24 um 10:55 schrieb Jani Nikula:
>>> Removal of the backlight include from fb.h uncovered an implicit
>>> dependency in powerpc asm/backlight.h. Add the explicit include.
>>>
>>> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
>>> Closes:=20
>>> https://lore.kernel.org/r/CA+G9fYsAk5TbqqxFC2W4oHLGA0CbTHMxbeq8QayFXTU7=
5YiueA@mail.gmail.com
>>> Fixes: 11b4eedfc87d ("fbdev: Do not include <linux/backlight.h> in=20
>>> header")
>>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>>> Cc: Helge Deller <deller@gmx.de>
>>> Cc: linux-fbdev@vger.kernel.org
>>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>>>
>>> ---
>>>
>>> Not even compile tested!
>>=20
>> That's one of the cases that's hard to catch unless you get the config=20
>> right.
>>=20
>>> ---
>>> =C2=A0 arch/powerpc/include/asm/backlight.h | 1 +
>>> =C2=A0 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/arch/powerpc/include/asm/backlight.h=20
>>> b/arch/powerpc/include/asm/backlight.h
>>> index 1b5eab62ed04..275d5bb9aa04 100644
>>> --- a/arch/powerpc/include/asm/backlight.h
>>> +++ b/arch/powerpc/include/asm/backlight.h
>>> @@ -10,6 +10,7 @@
>>> =C2=A0 #define __ASM_POWERPC_BACKLIGHT_H
>>> =C2=A0 #ifdef __KERNEL__
>>> +#include <linux/backlight.h>
>>=20
>> Thanks, but I think this should go directly into chipsfb.c. I would have=
=20
>> provided a patch already, if our mail server didn't have issues this=20
>> morning. Let me try again.
>
> asm/backlight.h needs it for struct backlight_device
>
> At least if you don't want to include linux/backlight.h in=20
> asm/backlight.h, then you need a forward declaration of struct=20
> backlight_device;

It's preferable for asm headers not to include linux headers (to avoid
loops), so a forward declaration would be better IMHO.

cheers