RE: [PATCH v3 6/6] cpufreq:amd-pstate: add quirk for the pstate CPPC capabilities missing

["Yuan, Perry" <Perry.Yuan@amd.com>]

[AMD Official Use Only - General]

> -----Original Message-----
> From: Oleksandr Natalenko <oleksandr@natalenko.name>
> Sent: Sunday, February 4, 2024 10:45 PM
> To: rafael.j.wysocki@intel.com; Limonciello, Mario
> <Mario.Limonciello@amd.com>; viresh.kumar@linaro.org; Huang, Ray
> <Ray.Huang@amd.com>; Shenoy, Gautham Ranjal
> <gautham.shenoy@amd.com>; Petkov, Borislav
> <Borislav.Petkov@amd.com>; Yuan, Perry <Perry.Yuan@amd.com>
> Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>; Du, Xiaojian <Xiaojian.Du@amd.com>; Meng,
> Li (Jassmine) <Li.Meng@amd.com>; linux-pm@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH v3 6/6] cpufreq:amd-pstate: add quirk for the pstate
> CPPC capabilities missing
>
> Hello.
>
> On neděle 4. února 2024 4:26:14 CET Perry Yuan wrote:
> > Add quirks table to get CPPC capabilities issue fixed by providing
> > correct perf or frequency values while driver loading.
> >
> > If CPPC capabilities are not defined in the ACPI tables or wrongly
> > defined by platform firmware, it needs to use quick to get those
> > issues fixed with correct workaround values to make pstate driver can
> > be loaded even though there are CPPC capabilities errors.
> >
> > The workaround will match the broken BIOS which lack of CPPC
> > capabilities nominal_freq and lowest_freq definition in the ACPI table.
> >
> > $ cat /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_freq
> > 0
> > $ cat /sys/devices/system/cpu/cpu0/acpi_cppc/nominal_freq
> > 0
> >
> > Signed-off-by: Perry Yuan <perry.yuan@amd.com>
> > ---
> >  drivers/cpufreq/amd-pstate.c | 49
> ++++++++++++++++++++++++++++++++++--
> >  include/linux/amd-pstate.h   |  6 +++++
> >  2 files changed, 53 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index 77effc3caf6c..25a6d8a808c4 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -67,6 +67,7 @@ static struct cpufreq_driver amd_pstate_epp_driver;
> > static int cppc_state = AMD_PSTATE_UNDEFINED;  static bool
> > cppc_enabled;  static bool amd_pstate_prefcore = true;
> > +static struct quirk_entry *quirks;
> >
> >  /*
> >   * AMD Energy Preference Performance (EPP) @@ -111,6 +112,33 @@
> > static unsigned int epp_values[] = {
> >
> >  typedef int (*cppc_mode_transition_fn)(int);
> >
> > +static struct quirk_entry quirk_amd_7k62 = {
> > +   .nominal_freq = 2600,
> > +   .lowest_freq = 550,
> > +};
> > +
> > +static int __init dmi_matched(const struct dmi_system_id *dmi) {
> > +   quirks = dmi->driver_data;
> > +   pr_info("hardware type %s found\n", dmi->ident);
> > +
> > +   return 1;
> > +}
> > +
> > +static const struct dmi_system_id amd_pstate_quirks_table[] __initconst
> = {
> > +   {
> > +           .callback = dmi_matched,
> > +           .ident = "AMD EPYC 7K62",
> > +           .matches = {
> > +                   DMI_MATCH(DMI_BIOS_VERSION, "5.14"),
> > +                   DMI_MATCH(DMI_BIOS_RELEASE, "12/12/2019");
>
> I think this is incorrect, and there should be a comma "," instead of
> semicolon ";" at the end of the string. Otherwise the build will fail.

Good catch, I made a mistake here, I found this after I sent it out,  have it fixed in V4.
Thanks for the review.

Perry.

>
> > +           },
> > +           .driver_data = &quirk_amd_7k62,
> > +   },
> > +   {}
> > +};
> > +MODULE_DEVICE_TABLE(dmi, amd_pstate_quirks_table);
> > +
> >  static inline int get_mode_idx_from_str(const char *str, size_t size)
> > {
> >     int i;
> > @@ -600,13 +628,19 @@ static void amd_pstate_adjust_perf(unsigned int
> > cpu,  static int amd_get_min_freq(struct amd_cpudata *cpudata)  {
> >     struct cppc_perf_caps cppc_perf;
> > +   u32 lowest_freq;
> >
> >     int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> >     if (ret)
> >             return ret;
> >
> > +   if (quirks && quirks->lowest_freq)
> > +           lowest_freq = quirks->lowest_freq;
> > +   else
> > +           lowest_freq = cppc_perf.lowest_freq;
> > +
> >     /* Switch to khz */
> > -   return cppc_perf.lowest_freq * 1000;
> > +   return lowest_freq * 1000;
> >  }
> >
> >  static int amd_get_max_freq(struct amd_cpudata *cpudata) @@ -635,12
> > +669,18 @@ static int amd_get_max_freq(struct amd_cpudata *cpudata)
> > static int amd_get_nominal_freq(struct amd_cpudata *cpudata)  {
> >     struct cppc_perf_caps cppc_perf;
> > +   u32 nominal_freq;
> >
> >     int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> >     if (ret)
> >             return ret;
> >
> > -   return cppc_perf.nominal_freq;
> > +   if (quirks && quirks->nominal_freq)
> > +           nominal_freq = quirks->nominal_freq;
> > +   else
> > +           nominal_freq = cppc_perf.nominal_freq;
> > +
> > +   return nominal_freq;
> >  }
> >
> >  static int amd_get_lowest_nonlinear_freq(struct amd_cpudata *cpudata)
> > @@ -1672,6 +1712,11 @@ static int __init amd_pstate_init(void)
> >     if (cpufreq_get_current_driver())
> >             return -EEXIST;
> >
> > +   quirks = NULL;
> > +
> > +   /* check if this machine need CPPC quirks */
> > +   dmi_check_system(amd_pstate_quirks_table);
> > +
> >     switch (cppc_state) {
> >     case AMD_PSTATE_UNDEFINED:
> >             /* Disable on the following configs by default:
> > diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> > index d21838835abd..7b2cbb892fd9 100644
> > --- a/include/linux/amd-pstate.h
> > +++ b/include/linux/amd-pstate.h
> > @@ -124,4 +124,10 @@ static const char * const
> amd_pstate_mode_string[] = {
> >     [AMD_PSTATE_GUIDED]      = "guided",
> >     NULL,
> >  };
> > +
> > +struct quirk_entry {
> > +   u32 nominal_freq;
> > +   u32 lowest_freq;
> > +};
> > +
> >  #endif /* _LINUX_AMD_PSTATE_H */
> >
>
>
> --
> Oleksandr Natalenko (post-factum)