Re: intel_pstate_get_hwp_cap on wrong CPU

[srinivas pandruvada <srinivas.pandruvada@linux.intel.com>]

Hi,

On Fri, 2024-05-31 at 16:01 +0200, Sebastian Andrzej Siewior wrote:
> On 2024-05-31 04:56:04 [-0700], srinivas pandruvada wrote:
> > > Would you mind letting
> > >   /sys/devices/system/cpu/intel_pstate/num_pstates
> > > 
> > > reporting something sane? Not 4294967285 but 0 for instance?
> > > Would
> > > that
> > > make sense?
> > > 
> > It should be some good value, usually less than 50. Do you see this
> > high number without even triggering condition, which caused
> > warning?
> 
> Nope, without the error I see 22. I think this went "-EIO + -EIO -1"
> which ended up as what I reported by chance. Never mind then.
> 
> > In your system, firmware changed performance notifying via ACPI.
> > That
> > method is deprecated for a while. You are using Haswell, which has
> > this
> > support. But deprecated from Skylake.
> 
> Okay. Anything I should change?
You can't on these models.

> 
> > > Did Sebastian _Reichel_ report it, too?
> > My mistake. I picked up wrong Sebastian. Sorry.
> 
> Ah okay. Then
> Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> 
> because it does not do read the MSR in the code path I reported.
> 
Thanks. I will post the patch to the mailing list with the correction.

-Srinivas

> > Thanks,
> > Srinivas
> Sebastian
>