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

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Date: Fri, 2 Feb 2024 09:55:03 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: "Yuan, Perry" <Perry.Yuan@....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 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@....com>
>> Sent: Friday, February 2, 2024 11:17 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 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@....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..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.

> 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 */
>