Re: [PATCH 3/5] ALSA: pcm - fix page conversion on non-coherent MIPS arch

[Ralf Baechle <ralf@linux-mips.org>]

On Thu, Nov 26, 2009 at 04:13:06PM +0100, Takashi Iwai wrote:

> The non-coherent MIPS arch doesn't give the correct address by a simple
> virt_to_page() for pages allocated via dma_alloc_coherent().
> 
> Original patch by Wu Zhangjin <wuzj@lemote.com>.  A proper check of the
> buffer allocation type was added to avoid the wrong conversion.

The origins of this patch go back far further.  The oldest patch I could
find which is a superset of this was written by Atsushi Nemoto and
various incarnations of it have been sumitted to and reject by me
a number of times through the years.

> Note that this doesn't fix perfectly: the pages should be marked with
> proper pgprot value.  This will be done in a future implementation like
> the conversion to dma_mmap_coherent().
> 
> Signed-off-by: Takashi Iwai <tiwai@suse.de>

So while this is ugly I don't think this patch will actually make the
the situation worse for any MIPS platform.  So with both eyes closed:

Acked-by: Ralf Baechle <ralf@linux-mips.org>

  Ralf