linux-kernel - Re: [PATCH] cpufreq: intel_pstate: Fix cpuinfo_cur

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Date:   Tue, 25 Jul 2017 17:35:34 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     Huaisheng HS1 Ye <yehs1@...ovo.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: intel_pstate: Fix cpuinfo_cur_freq after performance governor changes

On Monday, July 24, 2017 07:57:45 PM Srinivas Pandruvada wrote:
> On Tue, 2017-07-25 at 01:46 +0000, Huaisheng HS1 Ye wrote:
> > Hi Rafael,
> > 
> > If you delete "get" function implement within intel_pstate, the 
> > sysfs interface cpuinfo_cur_freq will display <unknown> all the
> > time. 
> cpuinfo_cur_freq by definition should show actual frequency HW
> frequency. 

Right.

> Unless I missed something. So Len Brown's patch should also
> take care of this to get from arch specific function is available.
> So in addition to Rafael's change, what about this?
> 
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 9bf97a3..29ec687 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -689,8 +689,13 @@ store_one(scaling_max_freq, max);
>  static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
>                                         char *buf)
>  {
> -       unsigned int cur_freq = __cpufreq_get(policy);
> +       unsigned int cur_freq;
>  
> +       cur_freq = arch_freq_get_on_cpu(policy->cpu);
> +       if (cur_freq)
> +               return sprintf(buf, "%u\n", cur_freq);
> +
> +       cur_freq = __cpufreq_get(policy);
>         if (cur_freq)
>                 return sprintf(buf, "%u\n", cur_freq);
> 

So also by definition cpuinfo_cur_freq should not return the same thing as
scaling_cur_freq.

I actually would like cpuinfo_cur_freq to not be present at all, I need to
check why it still shows up if ->get is not present.

Thanks,
Rafael