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Date: Tue, 30 Mar 2004 10:48:42 +0100
From: Peter Horton <phorton@bitbox.co.uk>
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To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
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Subject: Re: missing flush_dcache_page call in 2.4 kernel
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Atsushi Nemoto wrote:

>>>>>>On Sun, 28 Mar 2004 14:04:00 +0100, Peter Horton <pdh@colonel-panic.org> said:
>>>>>>            
>>>>>>
>pdh> I've ditched the original Cobalt hack in c-r4k.c, and am using
>pdh> the patch below instead. Seems to work okay ...
>
>+	for (; addr < (void *) end; addr += PAGE_SIZE)
>+		flush_data_cache_page((unsigned long) addr);
>
>dma_cache_wback() will be more efficient ?
>  
>
Well technically it should be dma_cache_wback_inv(), though they equate 
to the same function currently.

It would be more efficient, but the dma_cache_*() functions are only 
available under CONFIG_DMA_NONCOHERENT, and our problem has nothing to 
do with DMA coherency at all.

All we really need to do is add a flush_dcache_range(from,to) function. 
I'm working on this at the moment.

>Also, I personally think replacing all insb/insw/insl is a bit
>overkill.  I'd prefer redefine insb/insw/insl in asm-mips/ide.h, but
>I'm not sure it is enough. (really all ins[bwl] should take care of
>the cache inconsistency?)
>
>  
>
There maybe other block drivers (SCSI?) that use insb/insw/insl that 
would also cause us grief, but we could provide both versions of the 
functions and select them as necessary.

P.