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Re: [PATCH] MIPS: Fixups of ALSA memory maps

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH] MIPS: Fixups of ALSA memory maps
From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 16 Nov 2009 18:14:14 +0100
Cc: Wu Zhangjin <wuzhangjin@gmail.com>, Jaroslav Kysela <perex@perex.cz>, alsa-devel@alsa-project.org, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Wu Zhangjin <wuzj@lemote.com>
In-reply-to: <20091116170641.GD14948@linux-mips.org>
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References: <9cbcd06037c18288a6493459b8f3a6e1562eca77.1258389992.git.wuzhangjin@gmail.com> <20091116170641.GD14948@linux-mips.org>
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At Mon, 16 Nov 2009 18:06:41 +0100,
Ralf Baechle wrote:
> 
> On Tue, Nov 17, 2009 at 12:48:14AM +0800, Wu Zhangjin wrote:
> 
> > Seems this is MIPS specific, but it's not that easy to move this patch
> > into the arch/mips part, So, any better solution?
> > 
> > Thanks & Regards,
> >        Wu Zhangjin
> > 
> > ------------------------
> > 
> > The user application mmap audio dma regions must be dma-coherent. This
> > patch fix it.
> > 
> > Without this patch, artsd will fail on boot, and mplayer will exit with
> > "Segmentation fault". (this happens on YeeLoong netbook, fuloong2f
> > mini pc with snd_cs5535 audio card)
> > 
> > This is originally from the to-mips branch of
> > http://dev.lemote.com/code/linux_loongson, and contributed by Yanhua
> > from Lemote Inc.
> > 
> > Reported-by: qiaochong <qiaochong@gmail.com>
> > Signed-off-by: Wu Zhangjin <wuzj@lemote.com>
> 
> This issue is an old ghost still around, see:
> 
>    
> http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=20060124.132832.37533152.nemoto%40toshiba-tops.co.jp
> 
> which is a superset of your proposed patch and which itself is refering to
> an even older posting from 2003:
> 
>    
> http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=20030523215935.71373.qmail%40web11901.mail.yahoo.com
> 
> The #ifdef'ed solution doesn't cut it for sure.  Let's see what better we
> can find ...

Indeed.  My preference option is to deploy dma_mmap_coherent() to
possible architectures and use it commonly in the ALSA core code.

But, as a temporary workaround, I'm fine with ifdef until the API is
defined...


thanks,

Takashi

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