Re: [PATCH] enable readback to get HPET working on ATI SB4x00, kernel 2.6.35_rc5

From: Stephan Wolf
Date: Wed Jul 14 2010 - 12:40:34 EST


Am 14.07.2010 18:13, schrieb Linus Torvalds:
On Wed, Jul 14, 2010 at 8:55 AM, Stephan Wolf
<stephan@xxxxxxxxxxxxxxxxxxx> 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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