Date: Fri, 27 Nov 2009 09:36:06 +0100
Message-ID: <s5h4oogpdop.wl%tiwai@suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: wuzhangjin@gmail.com, Andreas Mohr <andi@lisas.de>,
       linux-kernel@vger.kernel.org
Subject: Re: snd_usb_audio OOPS on MIPSEL - is that the mmap issue?
In-Reply-To: <20091126181554.GB11737@linux-mips.org>
References: <20091125231211.GA19559@rhlx01.hs-esslingen.de>
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	<s5h7htdodov.wl%tiwai@suse.de>
	<20091126181554.GB11737@linux-mips.org>
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At Thu, 26 Nov 2009 18:15:54 +0000,
Ralf Baechle wrote:
> 
> On Thu, Nov 26, 2009 at 10:09:04AM +0100, Takashi Iwai wrote:
> 
> > I guess it won't, because usb audio driver provides its own page
> > callback.  It uses vmalloced buffer as the primary buffer, then
> > copies to the urb transfer buffer.  So, mmap should work as long as
> > the page returned from vmalloc_to_page() can be mapped.
> 
> You mean mapping a page that is mapped to the vmalloc area of the kernel
> also to userland?  That's a fairly safe way to create cache aliases on
> those platforms that suffer from them.

Yes.  Thanks for clarification!


Takashi
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