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Subject: Re: Linux 2.4.21-pre3-ac4
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Ross Biro <rossb@google.com>
Cc: Alan Cox <alan@redhat.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Date: 14 Jan 2003 18:52:49 +0100
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On Tue, 2003-01-14 at 18:49, Ross Biro wrote:
> Benjamin Herrenschmidt wrote:
> 
> >Ok, but PIIX runs on intel platforms with real IOs, so there is no need
> >to perform a read... If we go the hwif->IOSYNC() way, we might well set
> >it up to no-op on x86 PIO iops by default and read of alt-status on
> >other archs if it's safe enough on other controllers/drives...
> >
> I believe that this will corrupt any inprogress UDMA transfer on the 
> promise 20265 chip and probably others.  It would be better to read the 
> dma registers for the Promise controllers.

You mean on the chip's other channel ? As we discussed earlier, we don't
need to enforce this delay at all for DMA as we wait for the DMA
controller to complete in the interrupt anyway. Or did I miss a race ?

Ben.


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