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Re: mips ide disk dma problem

To: Ralf Baechle <ralf@oss.sgi.com>
Subject: Re: mips ide disk dma problem
From: "Tommy S. Christensen" <tommy.christensen@eicon.com>
Date: Tue, 14 Aug 2001 10:12:49 +0200
Cc: Barry Wu <wqb123@yahoo.com>, linux-mips@oss.sgi.com
References: <20010813130729.37581.qmail@web13908.mail.yahoo.com> <3B782CB0.AA24C7C8@eicon.com> <20010814071718.A5552@bacchus.dhis.org>
Sender: owner-linux-mips@oss.sgi.com
Ralf Baechle wrote:
> 
> On Mon, Aug 13, 2001 at 09:38:24PM +0200, Tommy S. Christensen wrote:
> 
> > Barry Wu wrote:
> > > I meet problems about mips ide disk. I find dma mode
> > > is different from other platform. We have to use
> > > dma_cache_wback_inv and vtonocache functions to work
> > > under DMA mode, I read pcnet32 ethernet driver,
> > > it works like that. I do not know if I have to support
> > > ide disk dma, what I have to do?
> >
> > Some MIPS'ification is needed to handle the caches.
> > You can try the patch below to drivers/block/ide-dma.c.
> >
> > I don't know about your IDE controller (our board have
> > a CMD PCI-648), but it may need some special handling also.
> 
> You're referencing a function that doesn't exist in the whole kernel.

vtonocache(p) is defined as KSEG1ADDR(virt_to_phys(p)).
This is for linux-2.2.12 from MIPS, remember.

> Aside it's a crude hack anyway.  If you have problems with caches use
> the API defined in Documentation/DMA-mapping.txt.

I don't see why this is a hack. Sure, the Dynamic DMA
interface is a lot cleaner, but it ends up with more or
less the same.

-Tommy

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