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Date: Mon, 5 Feb 2024 10:26:52 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: "Yuan, Perry" <Perry.Yuan@....com>,
Oleksandr Natalenko <oleksandr@...alenko.name>,
"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 v3 6/6] cpufreq:amd-pstate: add quirk for the pstate CPPC
capabilities missing
On 2/4/2024 20:29, Yuan, Perry wrote:
> [AMD Official Use Only - General]
>
>> -----Original Message-----
>> From: Oleksandr Natalenko <oleksandr@...alenko.name>
>> Sent: Sunday, February 4, 2024 10:45 PM
>> To: rafael.j.wysocki@...el.com; Limonciello, Mario
>> <Mario.Limonciello@....com>; viresh.kumar@...aro.org; Huang, Ray
>> <Ray.Huang@....com>; Shenoy, Gautham Ranjal
>> <gautham.shenoy@....com>; Petkov, Borislav
>> <Borislav.Petkov@....com>; Yuan, Perry <Perry.Yuan@....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 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@....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.
I'm still wondering if this is the right level of narrowness. Does the
quirk only apply to a single BIOS vendor? Or any other sysfs attributes
that can be generic to all affected systems?
Also would it perhaps make sense to rename dmi_matched to
dmi_matched_7k62_bios_bug and then in dmi_matched_7k62_bios_bug check
the model/family match. In that function you can only set
quirks = dmi->driver_data
If the right CPU applies then too.
>
> 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)
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