From: Linus Torvalds on
On Wed, Jul 14, 2010 at 8:55 AM, Stephan Wolf
<stephan(a)letzte-bankreihe.de> wrote:
>
> �After commit 30a564be9d9554c168a654eddc2165869cc0d7bf "x86, hpet: Restrict
> read back to affected ATI chipsets" hpet did not work anymore on HP nx6325.
> The machine hangs on booting until a keystroke was taken. After a short time
> machine hangs again until next keystroke. Applying the following patch
> solves the issue for me.

Ok, this makes sense. Bugs in the ATI chipset is why
'hpet_readback_cmp' exists in the first place. HOWEVER, clearly that
commit changed it to be about too few ATI chipsets.

So right now, for

- PCI_DEVICE_ID_ATI_SBX00_SMBUS:
force disable HPET MSI
force HPET readback

- PCI_DEVICE_ID_ATI_IXP400_SMBU
force-enable HPET
...and than your patch makes it force HPET readback

but that doesn't actually make much sense in the bigger picture,
because there are other ATI chipsets that are related and presumably
also affected. What about IXP[23]00_SMBUS? And what about the IXP7
series (SBX00 is IXP6, afaik)?

So I get the feeling that this is incomplete, or at least needs
thinking about those other ATI chipsets too.

Thomas? And I added Andreas to the cc, maybe he knows what's up.

Linus
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From: Stephan Wolf on
Am 14.07.2010 18:13, schrieb Linus Torvalds:
> On Wed, Jul 14, 2010 at 8:55 AM, Stephan Wolf
> <stephan(a)letzte-bankreihe.de> wrote:
>> After commit 30a564be9d9554c168a654eddc2165869cc0d7bf "x86, hpet: Restrict
>> read back to affected ATI chipsets" hpet did not work anymore on HP nx6325.
>> The machine hangs on booting until a keystroke was taken. After a short time
>> machine hangs again until next keystroke. Applying the following patch
>> solves the issue for me.
> Ok, this makes sense. Bugs in the ATI chipset is why
> 'hpet_readback_cmp' exists in the first place. HOWEVER, clearly that
> commit changed it to be about too few ATI chipsets.
>
> So right now, for
>
> - PCI_DEVICE_ID_ATI_SBX00_SMBUS:
> force disable HPET MSI
> force HPET readback
>
> - PCI_DEVICE_ID_ATI_IXP400_SMBU
> force-enable HPET
> ...and than your patch makes it force HPET readback
>
> but that doesn't actually make much sense in the bigger picture,
> because there are other ATI chipsets that are related and presumably
> also affected. What about IXP[23]00_SMBUS? And what about the IXP7
> series (SBX00 is IXP6, afaik)?
>
> So I get the feeling that this is incomplete, or at least needs
> thinking about those other ATI chipsets too.
>
> Thomas? And I added Andreas to the cc, maybe he knows what's up.
>
> Linus
>
Ok, I did not consider that msi is disabled at all on IXP400. Isn't it?
Maybe that the reason why it is works for me.

Stephan
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From: Linus Torvalds on
On Wed, Jul 14, 2010 at 11:11 AM, Borislav Petkov
<borislav.petkov(a)amd.com> wrote:
>
> I'll try to find out which chipsets are actually affected but in the
> meantime we might want to do a temporary fix by enabling the readback
> back(!) on all ATI chipsets so that we don't uncover anymore bugs like
> the one above, hmmm?

That sounds like the right solution for now, yes. Rather than make
the readback quirk depend on one particular SMBUS revision, make it
happen unconditionally for an AMD northbridge (or is the HPET in the
SB? I forget - somebody who knows the details and can test it on a
machine or two should do the actual patch).

Thomas?

Linus
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