linux-kernel - RE: [PATCH v7 1/6] cpufreq:amd-pstate: fix the nominal freq value set

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Date: Thu, 14 Mar 2024 06:09:20 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: "Shenoy, Gautham Ranjal" <gautham.shenoy@....com>
CC: "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>, "Limonciello,
 Mario" <Mario.Limonciello@....com>, "viresh.kumar@...aro.org"
	<viresh.kumar@...aro.org>, "Huang, Ray" <Ray.Huang@....com>, "Petkov,
 Borislav" <Borislav.Petkov@....com>, "Deucher, Alexander"
	<Alexander.Deucher@....com>, "Huang, Shimmer" <Shimmer.Huang@....com>, "Du,
 Xiaojian" <Xiaojian.Du@....com>, "Meng, Li (Jassmine)" <Li.Meng@....com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v7 1/6] cpufreq:amd-pstate: fix the nominal freq value set

[AMD Official Use Only - General]

 Hi Gautham

> -----Original Message-----
> From: Shenoy, Gautham Ranjal <gautham.shenoy@....com>
> Sent: Thursday, March 14, 2024 1:49 PM
> To: Yuan, Perry <Perry.Yuan@....com>
> Cc: rafael.j.wysocki@...el.com; Limonciello, Mario
> <Mario.Limonciello@....com>; viresh.kumar@...aro.org; Huang, Ray
> <Ray.Huang@....com>; Petkov, Borislav <Borislav.Petkov@....com>;
> Deucher, Alexander <Alexander.Deucher@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Du, Xiaojian <Xiaojian.Du@....com>; Meng,
> Li (Jassmine) <Li.Meng@....com>; linux-pm@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH v7 1/6] cpufreq:amd-pstate: fix the nominal freq value set
>
> Hello Perry,
>
> On Wed, Mar 13, 2024 at 05:59:13PM +0800, Perry Yuan wrote:
> > Address an untested error where the nominal_freq was returned in KHz
> > instead of the correct MHz units, this oversight led to a wrong
> > nominal_freq set and resued, it will cause the max frequency of core
> > to be initialized with a wrong frequency value.
>
> As I had mentioned in my review comment to v6 [1], cpudata->max_freq,
> cpudata->min_freq, cpudata->lowest_non_linear_freq are all in
> khz. With this patch, cpudata->nominal_freq will be in mhz.
>
> As Dhananjay confirmed [2], this patch breaks the reporting in
> /sys/devices/system/cpu/cpufreq/policyX/*_freq as some of them will be
> reported in mhz while some others in khz which breaks the expectation that all
> these sysfs values should be reported in khz.
>
> [cpufreq]# grep . *freq
> amd_pstate_lowest_nonlinear_freq:1804000   <----- in khz
> amd_pstate_max_freq:3514000                <----- in khz
> cpuinfo_max_freq:2151                      <----- in mhz
> cpuinfo_min_freq:400000                    <----- in khz
> scaling_cur_freq:2151                      <----- in mhz
> scaling_max_freq:2151                      <----- in mhz
> scaling_min_freq:2151                      <----- in mhz
> [cpufreq]# pwd
> /sys/devices/system/cpu/cpu0/cpufreq
>
> What am I missing ?

https://lore.kernel.org/lkml/42a36c7f788e0fb77d4be7575aab9c937e1773de.1710322310.git.perry.yuan@amd.com/
Changes from v3:
* fix the max frequency value to be KHz when cpb boost disabled(Gautham R. Shenoy)


The previous problem has been resolved by the new patchset of  cpb boost support

+       if (on)
+               policy->cpuinfo.max_freq = cpudata->max_freq;
+       else
+               policy->cpuinfo.max_freq = cpudata->nominal_freq * 1000;


The frequency values of cpuinfo are correct on my system.

amd_pstate_lowest_nonlinear_freq:1701000
amd_pstate_max_freq:3501000
cpuinfo_max_freq:3501000
cpuinfo_min_freq:400000
scaling_cur_freq:400000
scaling_max_freq:3501000
scaling_min_freq:400000

Perry.

>
> [1] https://lore.kernel.org/lkml/ZcRvoYZKdUEjBUHp@BLR-
> 5CG11610CF.amd.com/)
> [2] https://lore.kernel.org/lkml/1aecf2fc-2ea4-46ec-aaf2-
> 0dbbb11b5f8b@....com/
>
> >
> > Cc: stable@...r.kernel.org
> > Fixes: ec437d71db7 ("cpufreq: amd-pstate: Introduce a new AMD P-State
> > driver to support future processors")
> > Reviewed-by: Mario Limonciello <mario.limonciello@....com>
> > Signed-off-by: Perry Yuan <perry.yuan@....com>
>
> --
> Thanks and Regards
> gautham.
>
>
> > ---
> >  drivers/cpufreq/amd-pstate.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index 2015c9fcc3c9..3faa895b77b7
> 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -647,8 +647,7 @@ static int amd_get_nominal_freq(struct
> amd_cpudata *cpudata)
> >     if (ret)
> >             return ret;
> >
> > -   /* Switch to khz */
> > -   return cppc_perf.nominal_freq * 1000;
> > +   return cppc_perf.nominal_freq;
> >  }
> >
> >  static int amd_get_lowest_nonlinear_freq(struct amd_cpudata *cpudata)
> > --
> > 2.34.1
> >