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

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Date:	Wed, 14 Jul 2010 21:30:00 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
cc:	Stephan Wolf <stephan@...zte-bankreihe.de>,
	linux-kernel@...r.kernel.org,
	Andreas Herrmann <andreas.herrmann3@....com>
Subject: Re: [PATCH] enable readback to get HPET working on ATI SB4x00, kernel
 2.6.35_rc5

On Wed, 14 Jul 2010, Linus Torvalds wrote:

> 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.

Hmpf. The only report I ever got was against SBX00 and I can reproduce
on my own machine. My IXP400_SMBUS box works fine without the
readback.

/me is confused