Re: [PATCH] x86/intel: Disable HPET on another Intel Coffee Lake platform

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, Sep 22 2021 at 22:27, Rafael J. Wysocki wrote:
> On Tue, Sep 21, 2021 at 10:18 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>>
>> On Tue, Sep 21 2021 at 20:05, Rafael J. Wysocki wrote:
>> > On 9/19/2021 2:14 AM, Thomas Gleixner wrote:
>> >> What's the proper way to figure out whether PC10 is supported?
>> >
>> > I can't say without research.  I think it'd be sufficient to check if
>> > C10 is supported, because asking for it is the only way to get PC10.
>>
>> Do we have a common function for that or do I need to implement the
>> gazillionst CPUID query for that?
>
> intel_idle has intel_idle_verify_cstate() that works on MWAIT
> substates from CPUID.  It looks like this could be reused.

Not to me. That's some cpuidle/intel_idle specific check which depends
on cpuidle_state_table being set up which is not available during early
boot.

The question I was asking whether we have a central place where we can
retrieve such information w/o invoking CPUID over and over again and
applying voodoo checks on it.

Obviously we don't, which sucks.

Thanks,

        tglx