From: Carlos Corbacho <carlos@strangeworlds.co.uk>
To: "f.cecco77@tiscali.it" <f.cecco77@tiscali.it>, tglx@linutronix.de
Subject: Re: hpet on nforce4/MCP51 in asus a6t
Date: Mon, 4 Feb 2008 12:20:19 +0000
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[Adding tglx to CC as he knows more about HPET's than I]

On Sunday 03 February 2008 18:33:57 f.cecco77@tiscali.it wrote:
> Hello,
> I have  a asus a6t with nforce4/MCP51 chipset. I pass to kernel 2.6.24
> 32 bit the options acpi_use_timer_override and hpet=force, in this way
> and the timer IRQ ends up routed as  IO-APIC-edge instead of XT-PIC.
> With acpi_use_timer_override I just get:
>
> TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
>
> and it works through the IO-APIC.
>
> Instead the hpet is disabled and I  just get :
>
> Time: acpi_pm clocksource has been installed.
> Clocksource tsc unstable (delta = -85010975 ns)
>
> Is possible to have hpet working also with if the BIOS doesn't support
> it ?

One point before we start - MCP51 is nForce 5, not nForce 4 (which is CK804).

If my understanding is correct, acpi_use_timer_override is only a workaround 
required for those nForce 5 boards that don't enable the HPET for you.

So IIUC, you should be able to use either 'hpet=force' 
or 'acpi_use_timer_override', either of which should solve any timing issues 
you see, but you shouldn't need both (which should solve your problem of 
acpi_use_timer_override ignoring the HPET - it shouldn't be needed 
if 'hpet=force' enables the HPET).

-Carlos
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