Re: [PATCH][IDE] small cleanup for AMD/nVidia IDE driver

[Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>]

On Friday 03 of October 2003 21:51, Allen Martin wrote:
> > I've seen 2.4.x patches from Allen Martin@nVidia on lkml.
> > In UDMA133 patch he mentioned that UDMA should be programmed by mode,
> > not UDMA cycle timing on nVidia chipsets (probably the same
> > applies to AMD).
> > Can you comment on this?
>
> Yes, these controllers have a 1:1 mapping between UDMA mode and
> AMD_UDMA_TIMING value.  Trying to map UDMA mode to cycle time and then map
> back to UDMA mode is error prone, and cause for some of the ugly
> workarounds in the current driver.  My patch to add Ultra133 support just
> expands this ugliness, but works.
>
> The mapping is as follows:
>
> UDMA2 0
> UDMA1 1
> UDMA0 2
> UDMA3 4
> UDMA4 5
> UDMA5 6
> UDMA6 7

Thanks for explaining this.
Vojtech please consider it in your future patches. ;-)

> Other ACPI aware OS'es use an ACPI method to change IDE timing, so this is
> hidden from the OS.

Damn, I must take a look at ACPI specification 8-).

--bartlomiej