Re: ALSA on MIPS platform

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

On Tue, Aug 07, 2007 at 08:41:10PM +0200, Takashi Iwai wrote:

> > It's ALSA that is doing funny things here so there is no point in fixing
> > the arch code to work for ALSA.
> 
> Yep, but OTOH, the arch code doesn't provide a proper standard way to
> mmap the pages allocated via dma_alloc_coherent().  That's the missing
> piece, especially on mips and sparc.  ARM has already one.
> 
> My wish is implementing dma_mmap_coherent() on all architectures, so
> that the driver can use it safely without messy ifdefs.

Adding dma_mmap_coherent has been proposed in 2004 but the discussion for
some reason went nowhere because it apparently isn't implementable on
PARISC due to cache synonyms - on MIPS we'd solve those issues where they
exist by using uncached or writethrough mappings, as apropriate.

  Ralf