Re: [PATCH 02/20] ata_piix: unify code for programming PIO and MWDMAtimings

[Sergei Shtylyov]

Hello.

On 21-02-2011 14:58, Alan Cox wrote:

> > > >       PIO mode is setup by different code, and it takes care of the IORDY
> > > > setting according to the PIO rules (and it gets called). DMA mode setup should
> > > > just ignore the IORDY setting as in all other sane drivers.

> > > Well it can't ignore it - but if you mean just keep the bit as is then

> >      Yes, I mean this.

> > > that sounds sensible, have to see what the docs say happens if you ever
> > > set MWDMA without IORDY.

> >      Don't think they say anything on this matter but I can't imagine that
> > IORDY matters for DMA.

   ... unless the IE bit means something special (and undocumented) for DMA, 
if Intel so insists on setting it for every DMA mode.

> Sure - but it does matter for an ATAPI transaction with then has a DMA
> phase because those timings will be used for the command transfer which
> is PIO.

   So what? We've already setup PIO timings before the DMA ones. Why force 
the IE bit?

> Alan

WBR, Sergei
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