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    SubjectRe: [PATCH] MIPS: Fixups of ALSA memory maps
    On Mon, Nov 16, 2009 at 06:14:14PM +0100, Takashi Iwai 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...

    There is a MIPS platform which may be based on a variety of system
    controllers only one of which supports cache coherency. So we want to
    deciede at runtime not at compile time.

    Ralf


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