Subject: Re: Parallel ATA with libata status with the patches I'm working on
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org,
       bzolnier@gmail.com
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Date: Sat, 05 Nov 2005 10:19:03 +1100
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On Fri, 2005-11-04 at 23:10 +0000, Russell King wrote:
> On Fri, Nov 04, 2005 at 01:41:06PM +0000, Alan Cox wrote:
> > While writing the new sl82c05 driver I noticed a real nasty lurking in
> > the old code. According to the errata docs you have to reset the DMA
> > engine every transfer to work around chip errata. It also says that this
> > resets any other ATA transfer in progress.
> > 
> > If both channels are in use there is no locking between the channels to
> > stop a reset on one channel as DMA begins making a mess of the other
> > channel. Looks like serialize should be set on the driver ?
> 
> Possibly, though benh needs to comment.  (I think benh has the only
> hardware which has the possibility of both channels - the NetWinder
> only has one channel with one disk.)

I don't have this hw anymore, it was a design I worked on for my
previous employer, years ago, I don't have access to it anymore and the
company doesn't exist anymore.

Ben.


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