Re: [PATCH] Resurrect IT8172 IDE controller driver

[Sergei Shtylyov]

Hello.

Shane McDonald wrote:

> > Alan Cox wrote:

> > > > > It's 240, not 242 ns as 33 is actually 33.333.

> > > > The maximum values give cycle time of 480 ns menaing that the controller
> > > > doesn't support PIO mode 0. Hm...

> > > Even if you clear the enable for the timing register ?

> >  These fast timing bits are documented as reserved.

> The spec says that PIO mode 0 is supported, but Sergei is correct --
> the maximum values give a cycle time of 480 ns.  How can this be?  The
> old driver appeared to have tried to support PIO mode 0 by setting to
> the maximum.

>   Which fast timing bits are documented as reserved?  My spec has the
> IDE Drive 0/1 Recovery Time and IDE Drive 0/1 Pulse Width bits in it.
> Are there other timing bits that aren't documented in my spec?

   Off the top of my head: bits 0, 3, 4, and 7 at offset 0x40 are not 
reserved in PIIX/ICH -- they enable the programmable timings for PIO and/or 
DMA. If they were left cleared, 600 ns cycle (PIO mode 0) was used.

>   Please excuse my dumb question -- I'm a little over my head here.

> > > Alan

> Shane

MBR, Sergei
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