Re: [PATCH] cpufreq: amd-pstate: Add sysfs file for base frequency

[Mario Limonciello]

On 7/3/23 02:06, Huang Rui wrote:
> On Thu, Jun 29, 2023 at 09:54:54PM +0800, Limonciello, Mario wrote:
> > Some applications may want to query the base frequency to tell when
> > a processor is operating in boost.
> >
> > Tested-by: Wyes Karny <wyes.karny@xxxxxxx>
> > Reviewed-by: Wyes Karny <wyes.karny@xxxxxxx>
> > Co-developed-by: Perry Yuan <perry.yuan@xxxxxxx>
> > Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
> > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> > ---
> >   Documentation/admin-guide/pm/amd-pstate.rst |  4 ++++
> >   drivers/cpufreq/amd-pstate.c                | 15 +++++++++++++++
> >   2 files changed, 19 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> > index 1cf40f69278cd..e68267857e859 100644
> > --- a/Documentation/admin-guide/pm/amd-pstate.rst
> > +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> > @@ -281,6 +281,10 @@ integer values defined between 0 to 255 when EPP feature is enabled by platform
> >   firmware, if EPP feature is disabled, driver will ignore the written value
> >   This attribute is read-write.
> >   
> > +``base_frequency``
> > +	Shows the base frequency of the CPU. Frequencies above this will be in the
> > +  ``boost`` range. This attribute is read-only.
> > +
> >   Other performance and frequency values can be read back from
> >   ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
> >   
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index 81fba0dcbee99..0fec66b3f7241 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -1037,6 +1037,19 @@ static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
> >   	return ret < 0 ? ret : count;
> >   }
> >   
> > +static ssize_t show_base_frequency(struct cpufreq_policy *policy, char *buf)
> > +{
> > +	struct amd_cpudata *cpudata = policy->driver_data;
> > +	u32 nominal_freq;
> > +
> > +	nominal_freq = amd_get_nominal_freq(cpudata);
> > +	if (nominal_freq < 0)
> > +		return nominal_freq;
> > +
> > +	return sysfs_emit(buf, "%d\n", nominal_freq);
> > +}
>
> User can get it from nominal_freq at drivers/acpi/cppc_acpi.c:
>
> show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_freq);

Thanks for sharing that, I wasn't aware.  This patch is unnecessary indeed.

> Thanks,
> Ray
>
> > +
> > +cpufreq_freq_attr_ro(base_frequency);
> >   cpufreq_freq_attr_ro(amd_pstate_max_freq);
> >   cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
> >   
> > @@ -1049,6 +1062,7 @@ static struct freq_attr *amd_pstate_attr[] = {
> >   	&amd_pstate_max_freq,
> >   	&amd_pstate_lowest_nonlinear_freq,
> >   	&amd_pstate_highest_perf,
> > +	&base_frequency,
> >   	NULL,
> >   };
> >   
> > @@ -1058,6 +1072,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
> >   	&amd_pstate_highest_perf,
> >   	&energy_performance_preference,
> >   	&energy_performance_available_preferences,
> > +	&base_frequency,
> >   	NULL,
> >   };
> >   
> > --
> > 2.34.1