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

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Message-ID: <AANLkTim5fAwwhqP2J9pfOqeJACFf0OvK_MMZc1oZb3M4@mail.gmail.com>
Date:	Wed, 14 Jul 2010 09:13:39 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Stephan Wolf <stephan@...zte-bankreihe.de>
Cc:	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	Andreas Herrmann <andreas.herrmann3@....com>
Subject: Re: [PATCH] enable readback to get HPET working on ATI SB4x00, kernel 
	2.6.35_rc5

On Wed, Jul 14, 2010 at 8:55 AM, Stephan Wolf
<stephan@...zte-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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