linux-kernel - RE: [PATCH 2/7] cpufreq: amd_pstate: add module parameter to load amd pstate EPP driver

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Date:   Sun, 25 Sep 2022 16:58:52 +0000
From:   "Yuan, Perry" <Perry.Yuan@....com>
To:     "Limonciello, Mario" <Mario.Limonciello@....com>,
        "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "Huang, Ray" <Ray.Huang@....com>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>
CC:     "Sharma, Deepak" <Deepak.Sharma@....com>,
        "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Su, Jinzhou (Joe)" <Jinzhou.Su@....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 2/7] cpufreq: amd_pstate: add module parameter to load amd
 pstate EPP driver

[AMD Official Use Only - General]

Hi Mario. 

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Saturday, September 10, 2022 2:50 AM
> To: Yuan, Perry <Perry.Yuan@....com>; rafael.j.wysocki@...el.com; Huang,
> Ray <Ray.Huang@....com>; viresh.kumar@...aro.org
> Cc: Sharma, Deepak <Deepak.Sharma@....com>; Fontenot, Nathan
> <Nathan.Fontenot@....com>; Deucher, Alexander
> <Alexander.Deucher@....com>; Su, Jinzhou (Joe) <Jinzhou.Su@....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 2/7] cpufreq: amd_pstate: add module parameter to
> load amd pstate EPP driver
> 
> On 9/9/2022 11:45, Perry Yuan wrote:
> > The amd_pstate mode parameter will allow user to select which amd
> > pstate working mode as booting mode, amd_pstate instance or
> amd_pstate_epp instance.
> >
> > 1) amd_pstate instance is depending on the target operation mode.
> > 2) amd_pstate_epp instance is depending on the set_policy operation
> mode.It
> >     is also called active mode that AMD SMU has EPP algorithm to control the
> >     CPU runtime frequency according to the EPP set value and workload.
> >
> > Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> > ---
> >   drivers/cpufreq/amd-pstate.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index a2463f785322..451295284a26 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -58,6 +58,12 @@ module_param(shared_mem, bool, 0444);
> >   MODULE_PARM_DESC(shared_mem,
> >   		 "enable amd-pstate on processors with shared memory
> solution
> > (false = disabled (default), true = enabled)");
> >
> > +static bool epp_enabled = true;
> > +module_param(epp_enabled, bool, 0444);
> MODULE_PARM_DESC(epp_enabled,
> > +                "load amd_pstate or amd_pstate_epp (true =
> > +amd_pstate_epp driver instance (default), false = amd_pstate driver
> > +instance)");
> > +
> 
> If you're operating in EPP mode or not the kernel module is still 'amd-pstate'.
> So to a user I think this is a pretty confusing designation.
> 
> I would propose the following instead:
> 
>  > +static bool epp = true;
>  > +module_param(epp, bool, 0444);
>  > +MODULE_PARM_DESC(epp,
>  > +                "Enable energy performance preference (EPP) control");
> 

Make sense to me, get this changed in V2 like you suggested.
Thanks.

> > +
> >   static struct cpufreq_driver amd_pstate_driver;
> >
> >   /**