Re: [PATCH ide] : Increase WAIT_DRQ to support slow CF cards

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Hello.

Philippe De Muyter wrote:

From: Robert Hancock <hancockrwd@xxxxxxxxx>
Date: Mon, 26 Oct 2009 19:40:03 -0600

On Mon, Oct 26, 2009 at 7:19 PM, David Miller <davem@xxxxxxxxxxxxx> wrote:
Meanwhile we should provide a way for things to work, and
realistically the only way to do that currently is to bump the
WAIT_DRQ value to some large number.

And that's exactly the kind of patch I'm willing to accept for this.
I agree, it's sub-optimal but it helps.. if the user wants better
behavior they should a) fix it so that the card isn't using PIO, at
least if it supports DMA and b) not use drivers/ide..

Strangely enough, I also had no timeout problem if I started my kernel with
'ide=nodma', instead of increasing WAIT_DRQ.

   Hm, interesting...

 So I surmise that WAIT_DRQ is used in the dma case.


It's used only for the PIO write commands -- see do_rw_taskfile() in ide-taskfile.c... DMA commands don't require waiting for BSY=0, DRQ=1 condition.

Philippe

WBR, Sergei


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