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

[Philippe De Muyter <phdm@macqel.be>]

Hi David,

On Mon, Oct 26, 2009 at 06:43:18PM -0700, David Miller wrote:
> From: Robert Hancock <hancockrwd@gmail.com>
> Date: Mon, 26 Oct 2009 19:40:03 -0600
> 
> > On Mon, Oct 26, 2009 at 7:19 PM, David Miller <davem@davemloft.net> 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.  So I surmise that WAIT_DRQ
is used in the dma case.

> 
> Philippe's patch that started this thread uses "3 * HZ / 10"
> which isn't large enough for the SSD cases.  Can someone please
> post a patch that uses a large enough value?

How big a timeout do you want/accept ? Mark Lord wrote about SSD's in the mail
referred by Robert Hancock :
	It should probably be at least 500msec or more now.

Philippe