Re: [PATCH] cpufreq: intel_pstate: Fix cpuinfo_cur_freq after performance governor changes

[Rafael J. Wysocki]

On Tuesday, July 25, 2017 07:03:36 AM Huaisheng HS1 Ye wrote:
> Hi Srinivas,
> Your idea is great, but your patch at cpufreq.c will force all platforms to use scaling_cur_freq as first choice when userspace wants to access cpuinfo_cur_freq. It is ok for intel x86 platfrom but hard to say with other platforms.
> I modified it like that, it looks more reasonable. How about that?
> 
> Hi Rafael,
> Deleting "get" function pointer within intel_pstate would lead to sysfs
> interface cpuinfo_cur_freq disappearing, because of
> cpufreq_add_dev_interface will check "cpufreq_driver->get" for it.

Which is exactly what I want.

cpuinfo_cur_freq is bogus for intel_pstate and it should have never been
exported for this driver.

> Perhaps just return 0 with in intel_pstate_get would be a workaround for this
> issue, how about it?
> 
> I have tested this patch based on Purley platform, both Hardware and Software
> P-states works correct, we could get accurate and same frequency from
> cpuinfo_cur_freq and scaling_cur_freq.

But this is not correct.  These two attributes should not be expected to always
return the same value.

Thanks,
Rafael