linux-kernel - RE: [PATCH V3 4/7] cpufreq: Add a notification message that the highest perf has changed

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Message-ID: <DM4PR12MB6351B071214B7B698A6C8C86F7E3A@DM4PR12MB6351.namprd12.prod.outlook.com>
Date:   Fri, 25 Aug 2023 02:56:28 +0000
From:   "Meng, Li (Jassmine)" <Li.Meng@....com>
To:     "Karny, Wyes" <Wyes.Karny@....com>
CC:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        "Huang, Ray" <Ray.Huang@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
        "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Sharma, Deepak" <Deepak.Sharma@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        "Huang, Shimmer" <Shimmer.Huang@....com>,
        "Yuan, Perry" <Perry.Yuan@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Borislav Petkov <bp@...en8.de>
Subject: RE: [PATCH V3 4/7] cpufreq: Add a notification message that the
 highest perf has changed

[AMD Official Use Only - General]

Hello Wyes:

> -----Original Message-----
> From: Karny, Wyes <Wyes.Karny@....com>
> Sent: Thursday, August 24, 2023 7:19 PM
> To: Meng, Li (Jassmine) <Li.Meng@....com>
> Cc: Karny, Wyes <Wyes.Karny@....com>; Rafael J . Wysocki
> <rafael.j.wysocki@...el.com>; Huang, Ray <Ray.Huang@....com>; linux-
> pm@...r.kernel.org; linux-kernel@...r.kernel.org; x86@...nel.org; linux-
> acpi@...r.kernel.org; Shuah Khan <skhan@...uxfoundation.org>; linux-
> kselftest@...r.kernel.org; Fontenot, Nathan
> <Nathan.Fontenot@....com>; Sharma, Deepak
> <Deepak.Sharma@....com>; Deucher, Alexander
> <Alexander.Deucher@....com>; Limonciello, Mario
> <Mario.Limonciello@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Yuan, Perry <Perry.Yuan@....com>; Du,
> Xiaojian <Xiaojian.Du@....com>; Viresh Kumar <viresh.kumar@...aro.org>;
> Borislav Petkov <bp@...en8.de>
> Subject: Re: [PATCH V3 4/7] cpufreq: Add a notification message that the
> highest perf has changed
>
> On 24 Aug 10:12, Meng Li wrote:
> > ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85 can be
> > emmitted to cause the the OSPM to re-evaluate the highest performance
> > register. Add support for this event.
> >
> > Signed-off-by: Meng Li <li.meng@....com>
> > Link:
> > https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control
> > .html?highlight=cppc#cpc-continuous-performance-control
> > ---
> >  drivers/acpi/processor_driver.c |  6 ++++++
> >  drivers/cpufreq/cpufreq.c       | 13 +++++++++++++
> >  include/linux/cpufreq.h         |  4 ++++
> >  3 files changed, 23 insertions(+)
> >
> > diff --git a/drivers/acpi/processor_driver.c
> > b/drivers/acpi/processor_driver.c index 4bd16b3f0781..29b2fb68a35d
> > 100644
> > --- a/drivers/acpi/processor_driver.c
> > +++ b/drivers/acpi/processor_driver.c
> > @@ -27,6 +27,7 @@
> >  #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
> >  #define ACPI_PROCESSOR_NOTIFY_POWER        0x81
> >  #define ACPI_PROCESSOR_NOTIFY_THROTTLING   0x82
> > +#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED  0x85
> >
> >  MODULE_AUTHOR("Paul Diefenbaugh");
> >  MODULE_DESCRIPTION("ACPI Processor Driver"); @@ -83,6 +84,11 @@
> > static void acpi_processor_notify(acpi_handle handle, u32 event, void
> *data)
> >             acpi_bus_generate_netlink_event(device->pnp.device_class,
> >                                               dev_name(&device->dev),
> event, 0);
> >             break;
> > +   case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
> > +           cpufreq_update_highest_perf(pr->id);
> > +           acpi_bus_generate_netlink_event(device->pnp.device_class,
> > +                                             dev_name(&device->dev),
> event, 0);
> > +           break;
> >     default:
> >             acpi_handle_debug(handle, "Unsupported event [0x%x]\n",
> event);
> >             break;
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index 50bbc969ffe5..842357abfae6 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -2675,6 +2675,19 @@ void cpufreq_update_limits(unsigned int cpu)  }
> > EXPORT_SYMBOL_GPL(cpufreq_update_limits);
> >
> > +/**
> > + * cpufreq_update_highest_perf - Update highest performance for a
> given CPU.
> > + * @cpu: CPU to update the highest performance for.
> > + *
> > + * Invoke the driver's ->update_highest_perf callback if present  */
> > +void cpufreq_update_highest_perf(unsigned int cpu) {
> > +   if (cpufreq_driver->update_highest_perf)
> > +           cpufreq_driver->update_highest_perf(cpu);
> > +}
> > +EXPORT_SYMBOL_GPL(cpufreq_update_highest_perf);
> > +
> >
> /**********************************************************
> ***********
> >   *               BOOST                                                  *
> >
> >
> **********************************************************
> ***********/
> > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index
> > 9bf94ae08158..58106b3d9183 100644
> > --- a/include/linux/cpufreq.h
> > +++ b/include/linux/cpufreq.h
> > @@ -232,6 +232,7 @@ int cpufreq_get_policy(struct cpufreq_policy
> > *policy, unsigned int cpu);  void refresh_frequency_limits(struct
> > cpufreq_policy *policy);  void cpufreq_update_policy(unsigned int
> > cpu);  void cpufreq_update_limits(unsigned int cpu);
> > +void cpufreq_update_highest_perf(unsigned int cpu);
> >  bool have_governor_per_policy(void);
> >  bool cpufreq_supports_freq_invariance(void);
> >  struct kobject *get_governor_parent_kobj(struct cpufreq_policy
> > *policy); @@ -377,6 +378,9 @@ struct cpufreq_driver {
> >     /* Called to update policy limits on firmware notifications. */
> >     void            (*update_limits)(unsigned int cpu);
> >
> > +   /* Called to update highest performance on firmware notifications.
> */
> > +   void            (*update_highest_perf)(unsigned int cpu);
> > +
>
> Can we use the existing `update_limits` callback?
>
> Thanks,
> Wyes
[Meng, Li (Jassmine)]
I think there is a difference between the two functions.
When ACPI received ACPI_PROCESSOR_NOTIFY_PERFORMANCE event, it will call 'update_limits' to update policy data.
However 'update_highest_perf' handles the message ACPI_PROCESSOR_NOTIFY_HIGHEST_PERF_CHANGED.

> >     /* optional */
> >     int             (*bios_limit)(int cpu, unsigned int *limit);
> >
> > --
> > 2.34.1
> >