AMD Pstate Fixes And Enhancements

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 <[email protected]>

---
  drivers/cpufreq/amd-pstate.c | 59 ++++++++++++++++++++++++++++++++++--
  include/linux/amd-pstate.h   |  6 ++++
  2 files changed, 63 insertions(+), 2 deletions(-)

drivers/cpufreq/amd-pstate.c +5 -0

index 77effc3caf6c..874d8b663790 100644
@@ -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,
+};

drivers/cpufreq/amd-pstate.c +36 -2

+	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:

include/linux/amd-pstate.h +6 -0

index d21838835abd..7b2cbb892fd9 100644
@@ -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 */

-----Original Message-----
From: Limonciello, Mario <[email protected]>
Sent: Tuesday, February 6, 2024 11:46 PM
To: Yuan, Perry <[email protected]>; [email protected]; [email protected]; Huang, Ray <[email protected]>; Shenoy, Gautham Ranjal <[email protected]>; Petkov, Borislav <[email protected]>
Cc: Deucher, Alexander <[email protected]>; Huang, Shimmer <[email protected]>; Du, Xiaojian <[email protected]>; Meng, Li (Jassmine) <[email protected]>; [email protected]; linux- [email protected]
Subject: Re: [PATCH v4 6/6] cpufreq:amd-pstate: add quirk for the pstate CPPC capabilities missing

Quoted 5 lines · Perry Yuan

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,

Quoted 6 lines

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.

Quoted 8 lines

$ 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 <[email protected]>

---
  drivers/cpufreq/amd-pstate.c | 59

++++++++++++++++++++++++++++++++++--

Quoted 22 lines

  include/linux/amd-pstate.h   |  6 ++++
  2 files changed, 63 insertions(+), 2 deletions(-)

(quoted diff) +0 -0

b/drivers/cpufreq/amd-pstate.c index 77effc3caf6c..874d8b663790 100644

drivers/cpufreq/amd-pstate.c +1 -0

@@ -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);

drivers/cpufreq/amd-pstate.c +3 -0

+static struct quirk_entry quirk_amd_7k62 = {
+   .nominal_freq = 2600,
+   .lowest_freq = 550,

drivers/cpufreq/amd-pstate.c static unsigned int epp_values[] = {

Quoted 10 lines

drivers/cpufreq/amd-pstate.c +10 -0

+};
+
+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 &&

Quoted 1 line

+ boot_cpu_has(X86_FEATURE_ZEN2)) {

I think you should use one or the other (17/31) or (X86_FEATURE_ZEN2).

drivers/cpufreq/amd-pstate.c static unsigned int epp_values[] = { · line 130

Quoted 3 lines

drivers/cpufreq/amd-pstate.c +2 -0

+           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"

drivers/cpufreq/amd-pstate.c static unsigned int epp_values[] = { · line 134

Quoted 5 lines

drivers/cpufreq/amd-pstate.c +4 -0

+           return 1;
+   }
+
+

Only need one newline needed here.

drivers/cpufreq/amd-pstate.c static unsigned int epp_values[] = {

Quoted 5 lines

drivers/cpufreq/amd-pstate.c +4 -0

+   return 0;
+}
+
+static const struct dmi_system_id amd_pstate_quirks_table[] __initconst

= {

drivers/cpufreq/amd-pstate.c static void amd_pstate_adjust_perf(unsigned int

Quoted 17 lines

drivers/cpufreq/amd-pstate.c +13 -0

+   {
+           .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,

include/linux/amd-pstate.h static const char * const

Quoted 57 lines

drivers/cpufreq/amd-pstate.c +15 -2

  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;

drivers/cpufreq/amd-pstate.c +5 -0

+   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:

include/linux/amd-pstate.h +0 -0

index d21838835abd..7b2cbb892fd9 100644
@@ -124,4 +124,10 @@ static const char * const

amd_pstate_mode_string[] = {

Quoted 10 lines

include/linux/amd-pstate.h +6 -0

    [AMD_PSTATE_GUIDED]      = "guided",
    NULL,
  };
+
+struct quirk_entry {
+   u32 nominal_freq;
+   u32 lowest_freq;
+};
+
  #endif /* _LINUX_AMD_PSTATE_H */