RE: [PATCH v2 6/6] cpufreq:amd-pstate: add quirk for the pstate CPPC capabilities missing

[Yuan, Perry]

[AMD Official Use Only - General]

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@xxxxxxx>
> Sent: Friday, February 2, 2024 11:55 PM
> To: Yuan, Perry <Perry.Yuan@xxxxxxx>; rafael.j.wysocki@xxxxxxxxx;
> viresh.kumar@xxxxxxxxxx; Huang, Ray <Ray.Huang@xxxxxxx>; Shenoy,
> Gautham Ranjal <gautham.shenoy@xxxxxxx>; Petkov, Borislav
> <Borislav.Petkov@xxxxxxx>
> Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; Du, Xiaojian <Xiaojian.Du@xxxxxxx>; Meng,
> Li (Jassmine) <Li.Meng@xxxxxxx>; linux-pm@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 6/6] cpufreq:amd-pstate: add quirk for the pstate
> CPPC capabilities missing
>
> On 2/2/2024 09:35, Yuan, Perry wrote:
> > [AMD Official Use Only - General]
> >
> >   Hi Mario,
> >
> >> -----Original Message-----
> >> From: Limonciello, Mario <Mario.Limonciello@xxxxxxx>
> >> Sent: Friday, February 2, 2024 11:17 PM
> >> To: Yuan, Perry <Perry.Yuan@xxxxxxx>; rafael.j.wysocki@xxxxxxxxx;
> >> viresh.kumar@xxxxxxxxxx; Huang, Ray <Ray.Huang@xxxxxxx>; Shenoy,
> >> Gautham Ranjal <gautham.shenoy@xxxxxxx>; Petkov, Borislav
> >> <Borislav.Petkov@xxxxxxx>
> >> Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Huang,
> Shimmer
> >> <Shimmer.Huang@xxxxxxx>; Du, Xiaojian <Xiaojian.Du@xxxxxxx>;
> Meng, Li
> >> (Jassmine) <Li.Meng@xxxxxxx>; linux-pm@xxxxxxxxxxxxxxx; linux-
> >> kernel@xxxxxxxxxxxxxxx
> >> Subject: Re: [PATCH v2 6/6] cpufreq:amd-pstate: add quirk for the
> >> pstate CPPC capabilities missing
> >>
> >> On 2/2/2024 02:55, Perry Yuan wrote:
> >>> Add quirk 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.
> >>>
> >>> Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
> >>> ---
> >>>    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..4d426516abb9
> >>> 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_PRODUCT_VERSION, "C1"),
> >>> +                   DMI_MATCH(DMI_PRODUCT_SERIAL,
> >> "FX19911000028")
> >>
> >> I saw your response to v1, but really this is too narrow for upstream.
> >> It's literally applying to a SINGLE system.
> >>
> >> I feel the rest of the patch is fine, but we shouldn't be adding
> >> single system quirks.
> >
> > How about change to match the BIOS version ?
> > Actually, the issue should be impacting all the systems which have the
> same broken BIOS.
> >
>
> Yeah it does sound like a BIOS defect; so this is a reasonable alternative.  Just
> make sure that you only apply it to the necessary systems with this change.
>

Agreed,  let me change to match BIOS version in V3.
Thanks for the feedback!

Perry.

> > 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 */
> >