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Subject: Re: Automatic device driver back-porting with media_build
To: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: linux-media <linux-media@vger.kernel.org>,
	Hans Verkuil <hans.verkuil@cisco.com>
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From: Mason <slash.tmp@free.fr>
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Date: Thu, 17 Dec 2015 17:48:57 +0100
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On 17/12/2015 17:09, Mauro Carvalho Chehab wrote:
> Em Thu, 17 Dec 2015 16:32:54 +0100
> Mason <slash.tmp@free.fr> escreveu:
> 
>> I wanted to fix the NEED_WRITEL_RELAXED warning, but I don't know Perl.
>>
>> v4l/scripts/make_config_compat.pl
>>
>> check_files_for_func("writel_relaxed", "NEED_WRITEL_RELAXED", "include/asm-generic/io.h");
>> incorrectly outputs
>> #define NEED_WRITEL_RELAXED 1
>>
>>
>> In file included from <command-line>:0:0:
>> /tmp/sandbox/media_build/v4l/compat.h:1568:0: warning: "writel_relaxed" redefined
>>  #define writel_relaxed writel
>>  ^
>> In file included from include/linux/scatterlist.h:10:0,
>>                  from /tmp/sandbox/media_build/v4l/compat.h:1255,
>>                  from <command-line>:0:
>> /tmp/sandbox/custom-linux-3.4/arch/arm/include/asm/io.h:235:0: note: this is the location of the previous definition
>>  #define writel_relaxed(v,c) ((void)__raw_writel((__force u32) \
>>  ^
>>
>> Shouldn't the script examine arch/$ARCH/include/asm/io.h instead of
>> include/asm-generic/io.h ? (Or perhaps both?)
>>
>> Does make_config_compat.pl know about ARCH?
> 
> No to both. When you do a "make init" on the Kernel repository, it
> will evaluate the ARCH vars.
> 
> This is also needed for the media build to work, as it needs to
> check what CONFIG vars are enabled on the targeted Kernel.

I downloaded the vanilla version of my custom kernel: linux-3.4.39.tar.xz

Even then, NEED_WRITEL_RELAXED is incorrectly defined.

How do you propose to fix this bug?

$ grep writel_relaxed arch/arm/include/asm/io.h
#define writel_relaxed(v,c)	((void)__raw_writel((__force u32) \
#define writel(v,c)		({ __iowmb(); writel_relaxed(v,c); })

$ grep writel_relaxed arch/x86/include/asm/io.h
$ grep -r writel_relaxed include

> As I said before, heavily patched Kernel. It seems that the network stack
> was updated to some newer version. The media_build backport considers
> only the upstream Kernels. In the specific case of 3.4, it is known
> to build fine with Kernel linux-3.4.27. See:
> 	http://hverkuil.home.xs4all.nl/logs/Wednesday.log

I will keep trying to get something to compile.

Regards.