Re: [PATCH v3 6/6] cpufreq:amd-pstate: add quirk for the pstate CPPC capabilities missing
From: Mario Limonciello
Date: Mon Feb 05 2024 - 11:27:10 EST
On 2/4/2024 20:29, Yuan, Perry wrote:
[AMD Official Use Only - General]
-----Original Message-----
From: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>
Sent: Sunday, February 4, 2024 10:45 PM
To: rafael.j.wysocki@xxxxxxxxx; Limonciello, Mario
<Mario.Limonciello@xxxxxxx>; viresh.kumar@xxxxxxxxxx; Huang, Ray
<Ray.Huang@xxxxxxx>; Shenoy, Gautham Ranjal
<gautham.shenoy@xxxxxxx>; Petkov, Borislav
<Borislav.Petkov@xxxxxxx>; Yuan, Perry <Perry.Yuan@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 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@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..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)