Re: [PATCH] mips: Add dma_mmap_coherent()

[tsbogend@alpha.franken.de (Thomas Bogendoerfer)]

On Fri, Aug 22, 2008 at 12:23:48PM +0200, Takashi Iwai wrote:
>       unsigned long prot = pgprot_val(_prot) & ~_CACHE_MASK;
> #ifdef CONFIG_SGI_IP32
> #ifdef CONFIG_CPU_R10000
>       prot = prot | _CACHE_UNCACHED_ACCELERATED;
> #else
>       prot = prot | _CACHE_CACHABLE_NO_WA;
> #endif
> #else
>       prot = prot | _CACHE_UNCACHED;
> #endif
>       return __pgprot(prot);

this won't work for recording channels on IP32, because the write trough
mapping will hide updates done via DMA.

I'd start with just

prot |= _CACHE_UNCACHED

and if some MIPS system needs more specific treatment, we just add
that later.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessary a
good idea.                                                [ RFC1925, 2.3 ]