linux-mips
[Top] [All Lists]

Re: [PATCH] mips: Add dma_mmap_coherent()

To: tsbogend@alpha.franken.de (Thomas Bogendoerfer)
Subject: Re: [PATCH] mips: Add dma_mmap_coherent()
From: Takashi Iwai <tiwai@suse.de>
Date: Fri, 22 Aug 2008 16:47:45 +0200
Cc: ralf@linux-mips.org, James Bottomley <James.Bottomley@HansenPartnership.com>, linux-mips@linux-mips.org, Parisc List <linux-parisc@vger.kernel.org>
In-reply-to: <20080822143622.GA8413@alpha.franken.de>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <s5hzln7vd9d.wl%tiwai@suse.de> <1219255088.3258.45.camel@localhost.localdomain> <s5hr68ivfer.wl%tiwai@suse.de> <1219326912.3265.2.camel@localhost.localdomain> <s5hhc9enyqa.wl%tiwai@suse.de> <s5hfxoynyn4.wl%tiwai@suse.de> <20080821214118.GA12516@alpha.franken.de> <s5hbpzl8tvz.wl%tiwai@suse.de> <20080822094131.GA6717@alpha.franken.de> <s5h7ia9nya3.wl%tiwai@suse.de> <20080822143622.GA8413@alpha.franken.de>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Wanderlust/2.12.0 (Your Wildest Dreams) SEMI/1.14.6 (Maruoka) FLIM/1.14.7 (Sanjō) APEL/10.6 Emacs/22.2 (x86_64-suse-linux-gnu) MULE/5.0 (SAKAKI)
At Fri, 22 Aug 2008 16:36:22 +0200,
Thomas Bogendoerfer wrote:
> 
> 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.

Hmm, not so easy...

> I'd start with just
> 
> prot |= _CACHE_UNCACHED
> 
> and if some MIPS system needs more specific treatment, we just add
> that later.

OK, then it's essentially pgprog_noncached() as in my second patch.


Thanks!

Takashi

<Prev in Thread] Current Thread [Next in Thread>