Re: AMD760MPX: bogus chispset ? (was PROBLEM: sound is stutter, sizzle with lasts kernel releases)

From: xi (
Date: Fri Jul 11 2003 - 16:04:39 EST

Alan Cox wrote:
> On Gwe, 2003-07-11 at 18:02, xi wrote:
>>Now I have done some investigations, and I think I have found the
>>problem: It has appeared between kernel-2.4.18-pre9 and kernel-2.4.18-rc1
>>If I am not wrong, between these two versions, Alan Cox did a change in
>>drivers/pci/quirks.c and this is this change which cause the problem.
> As I read the documentation the other change is also required in this
> situation to avoid a chipset lockup. It might be worth you rechecking
> the AMD errata docs for 762/768 again to be sure I didnt screw up and
> there are not newer rules for other revisions.

Ok, I have rechecked the errata docs. I have not found any
recommandation change for PCI compliance configuration registers.

And one interesting thing:
in the AMD762 datasheet (24462.pdf) page 231 (Recommanded BIOS
settings), I can see this: "Numerical Values shown with h or b are
preferred settings." ; and AMD recommand this:
-> set bits 2 and 1 of register 0x4C to "0b"
-> set bits 23 and 3 respectively to "0b" and "1b"

I can confirm that these settings works much more better, even if they
don't exactly follow PCI specs. And I don't think this is specific to my
  cards since I have tested others.
Furthermore, my AMD762 is revision B1 (just before the last one: C0),
and my AMD768 revision is B2, the last one.

Would you accept I make a patch which doesn't make any change in these
registers at least up to AMD762 revision B1 (ie keeping recommanded
values from AMD) ?
Or could you propose an other solution ?


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