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Date: Fri, 5 Sep 2008 14:42:03 +0200
From: Andreas Herrmann <andreas.herrmann3@amd.com>
To: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert commit e8aa4667baf74dfd85fbaab86861465acb811085
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On Thu, Sep 04, 2008 at 06:14:38PM +0200, Thomas Gleixner wrote:
> On Thu, 4 Sep 2008, Ingo Molnar wrote:
> 
> > 
> > * Andreas Herrmann <andreas.herrmann3@amd.com> wrote:
> > 
> > > This reverts commit e8aa4667baf74dfd85fbaab86861465acb811085
> > >  (x86: enable hpet=force for AMD SB400)
> > > 
> > > Since ATI/AMD decided not to support HPET on SB4xx it doesn't
> > > make sense to enable this unsupported feature.
> > > (I was not aware of this when submitting the quirk.)
> > > 
> > > If a system with SB4xx chipset provides an ACPI HPET table and does
> > > not boot, "nohpet" should be used as kernel parameter.
> > > 
> > > Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
> > 
> > applied to tip/x86/urgent, thanks Andreas. I guess a system broke due to 
> > this commit?
> 
> Hmm, why do we remove something which needs to be force enabled by the
> user anyway ?  

> Is the HPET on these systems not working at all so the force enable
> code is useless ?

The current quirk is incomplete. Some more chipset fiddling has to be
done to enable HPET interrupts. I have a patch that would do this.
And from my tests it seems to work faultlessly.

But the official statement is that HPET is not supported on SB4XX.

Thus there are 2 alternatives:
(1) Remove the current (incomplete) quirk.
(2) Extent the quirk.
    But whoever forces HPET would use it on his own risk.

I decided to do (1) because it's safest.
Other opinions?


Regards,

Andreas