Re: [patch] My AMD IDE driver, v2.7

[Vojtech Pavlik <vojtech@suse.cz>]

On Tue, Mar 12, 2002 at 05:26:20PM +0100, Martin Dalecki wrote:
> Vojtech Pavlik wrote:
> 
> 
> > Well, as much as I'd like to use safe pre-computed register values for
> > the chips, that ain't possible - even when we assumed the system bus
> > (PCI, VLB, whatever) was always 33 MHz, still the drives have various
> > ideas about what DMA and PIO modes should look like, see the tDMA and
> > tPIO entries in hdparm -t.  
> 
> Yes yes yes of course some of the drivers are confused. And I don't
> argue that precomputation is adequate right now. It just wasn't for
> the CMD640 those times... I only wanted to reffer to history and
> why my timings where different then the computed.

We may want to compare your original timings to what ide-timing.[ch]
will compute ...

> > So, arithmetics has to stay. Hopefully just one instance in
> > ide-timing.c.
> > 
> > 
> >>>I plan to focus on the most important drivers first, to fix and clean
> >>>them, working with the authors where possible.
> >>>
> >>PIIX na VIA comes to mind first ;-)...
> >>
> > 
> > VIA is already OK, well, it has my name in it. :) AMD is now also (well,
> 
> Oh of course I was reffering to VIA as important.
> 
> > that one wasn't broken, just ugly), SiS is being revamped by Lionel
> > Bouton (whom I'm trying to help as much as I can), so yes, PIIX would be
> > next.
> 
> I swallowed his SiS stuff already, since my home main machine is
> a SiS735 based board. (Awfoul cheap that thing and quite good price/performance
> ratio ;-).

As you can guess, I have mostly VIA machines around here. One SiS, too,
but that's an embedded board.

> > PIIX and ICH are pretty crazy hardware from the design perspective, very
> > legacy-bound back to the first Intel PIIX chip. And the driver for these
> 
> Yes I "love" the bound together DMA areas as well ;-).

And the SIDETIM register is just a kyooot idea. :)

> > in the kernel has similarly evolved following the hardware. However, it
> > doesn't seem to be wrong at the first glance. Nevertheless, I'll take a
> > look at it. Unfortunately, I don't have any Intel hardware at hand to
> > test it with.
> 
> Just another hint: dmaproc is silly nomenclature is should be
> dma_strategy <- this would better reflect it's purpose.

Dmaproc? Well that's a do-everything-possible-with-default-fallbacks
function. Quite an interesting approach, though I'd be much happier
without it.

Btw, do you know that the chipset and drives are tuned twice each boot?
First they're configured to PIO and half a second later to DMA (or PIO)
again ...

-- 
Vojtech Pavlik
SuSE Labs