Re: [PATCH] cpufreq: amd-pstate: Add sysfs file for base frequency

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On 7/3/23 02:06, Huang Rui wrote:
On Thu, Jun 29, 2023 at 09:54:54PM +0800, Limonciello, Mario wrote:
Some applications may want to query the base frequency to tell when
a processor is operating in boost.

Tested-by: Wyes Karny <wyes.karny@xxxxxxx>
Reviewed-by: Wyes Karny <wyes.karny@xxxxxxx>
Co-developed-by: Perry Yuan <perry.yuan@xxxxxxx>
Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
  Documentation/admin-guide/pm/amd-pstate.rst |  4 ++++
  drivers/cpufreq/amd-pstate.c                | 15 +++++++++++++++
  2 files changed, 19 insertions(+)

diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
index 1cf40f69278cd..e68267857e859 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -281,6 +281,10 @@ integer values defined between 0 to 255 when EPP feature is enabled by platform
  firmware, if EPP feature is disabled, driver will ignore the written value
  This attribute is read-write.
+``base_frequency``
+	Shows the base frequency of the CPU. Frequencies above this will be in the
+  ``boost`` range. This attribute is read-only.
+
  Other performance and frequency values can be read back from
  ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 81fba0dcbee99..0fec66b3f7241 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1037,6 +1037,19 @@ static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
  	return ret < 0 ? ret : count;
  }
+static ssize_t show_base_frequency(struct cpufreq_policy *policy, char *buf)
+{
+	struct amd_cpudata *cpudata = policy->driver_data;
+	u32 nominal_freq;
+
+	nominal_freq = amd_get_nominal_freq(cpudata);
+	if (nominal_freq < 0)
+		return nominal_freq;
+
+	return sysfs_emit(buf, "%d\n", nominal_freq);
+}

User can get it from nominal_freq at drivers/acpi/cppc_acpi.c:

show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_freq);

Thanks for sharing that, I wasn't aware.  This patch is unnecessary indeed.


Thanks,
Ray

+
+cpufreq_freq_attr_ro(base_frequency);
  cpufreq_freq_attr_ro(amd_pstate_max_freq);
  cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
@@ -1049,6 +1062,7 @@ static struct freq_attr *amd_pstate_attr[] = {
  	&amd_pstate_max_freq,
  	&amd_pstate_lowest_nonlinear_freq,
  	&amd_pstate_highest_perf,
+	&base_frequency,
  	NULL,
  };
@@ -1058,6 +1072,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
  	&amd_pstate_highest_perf,
  	&energy_performance_preference,
  	&energy_performance_available_preferences,
+	&base_frequency,
  	NULL,
  };
--
2.34.1





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