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Date: Wed, 7 Feb 2024 07:13:50 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: "Limonciello, Mario" <Mario.Limonciello@....com>,
"rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>, "Huang, Ray"
<Ray.Huang@....com>, "Shenoy, Gautham Ranjal" <gautham.shenoy@....com>,
"Petkov, Borislav" <Borislav.Petkov@....com>
CC: "Deucher, Alexander" <Alexander.Deucher@....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 v4 6/6] cpufreq:amd-pstate: add quirk for the pstate CPPC
capabilities missing
[AMD Official Use Only - General]
Hi Mario,
> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Tuesday, February 6, 2024 11:46 PM
> To: Yuan, Perry <Perry.Yuan@....com>; rafael.j.wysocki@...el.com;
> viresh.kumar@...aro.org; Huang, Ray <Ray.Huang@....com>; Shenoy,
> Gautham Ranjal <gautham.shenoy@....com>; Petkov, Borislav
> <Borislav.Petkov@....com>
> Cc: Deucher, Alexander <Alexander.Deucher@....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 v4 6/6] cpufreq:amd-pstate: add quirk for the pstate
> CPPC capabilities missing
>
> On 2/5/2024 22:33, 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
> s,quick,a quirk,
> > 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@....com>
> > ---
> > drivers/cpufreq/amd-pstate.c | 59
> ++++++++++++++++++++++++++++++++++--
> > include/linux/amd-pstate.h | 6 ++++
> > 2 files changed, 63 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index 77effc3caf6c..874d8b663790 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 +112,43 @@
> > 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_7k62_bios_bug(const struct
> > +dmi_system_id *dmi) {
> > + /**
> > + * match the broken bios for family 17h, model 31h processor
> > + * broken BIOS lack of nominal_freq and lowest_freq capabilities
> > + * definition in ACPI tables
> > + */
> > + if (boot_cpu_data.x86 == 0x17 && boot_cpu_data.x86_model ==
> 0x31 &&
> > + boot_cpu_has(X86_FEATURE_ZEN2)) {
>
> I think you should use one or the other (17/31) or (X86_FEATURE_ZEN2).
Looks like it makes sense to match ZEN2 flag and specific BIOS version. That will cover the broken BIOS and CPU.
>
> > + quirks = dmi->driver_data;
> > + pr_info("hardware type %s found\n", dmi->ident);
>
> I think a better message explains what is happening. For example:
> "Overriding nominal and lowest frequencies for %s\n"
Made suggestions to v5.
>
> > + return 1;
> > + }
> > +
> > +
>
> Only need one newline needed here.
Fixed in V5.
Thanks for the review comments!
Perry.
>
> > + return 0;
> > +}
> > +
> > +static const struct dmi_system_id amd_pstate_quirks_table[] __initconst
> = {
> > + {
> > + .callback = dmi_matched_7k62_bios_bug,
> > + .ident = "AMD EPYC 7K62",
> > + .matches = {
> > + DMI_MATCH(DMI_BIOS_VERSION, "5.14"),
> > + DMI_MATCH(DMI_BIOS_RELEASE, "12/12/2019"),
> > + },
> > + .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 +638,19 @@ 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
> > +679,18 @@ 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 +1722,11 @@ 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 */
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