Add documentation about the newly added pm_policy node in sysfs.
Signed-off-by: Lijo Lazar <lijo.lazar@xxxxxxx>
---
v5: Update documentation to reflect pm_policy nodes and sub nodes for each
policy type
Documentation/gpu/amdgpu/thermal.rst | 6 ++++
drivers/gpu/drm/amd/pm/amdgpu_pm.c | 53 ++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)
diff --git a/Documentation/gpu/amdgpu/thermal.rst b/Documentation/gpu/amdgpu/thermal.rst
index 2f6166f81e6a..6d942b5c58f0 100644
--- a/Documentation/gpu/amdgpu/thermal.rst
+++ b/Documentation/gpu/amdgpu/thermal.rst
@@ -49,6 +49,12 @@ pp_power_profile_mode
.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
:doc: pp_power_profile_mode
+pm_policy
+---------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+ :doc: pm_policy
+
\*_busy_percent
---------------
diff --git a/drivers/gpu/drm/amd/pm/amdgpu_pm.c b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
index 5ff7783dfc43..3e5ffb83f398 100644
--- a/drivers/gpu/drm/amd/pm/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
@@ -2220,6 +2220,59 @@ struct amdgpu_pm_policy_attr {
enum pp_pm_policy id;
};
+/**
+ * DOC: pm_policy
+ *
+ * Certain SOCs can support different power policies to optimize application
+ * performance. However, this policy is provided only at SOC level and not at a
+ * per-process level. This is useful especially when entire SOC is utilized for
+ * dedicated workload.
+ *
+ * The amdgpu driver provides a sysfs API for selecting the policy. Presently,
+ * only two types of policies are supported through this interface.
+ *
+ * Pstate Policy Selection - This is to select different Pstate profiles which
+ * decides clock/throttling preferences.
+ *
+ * XGMI PLPD Policy Selection - When multiple devices are connected over XGMI,
+ * this helps to select policy to be applied for per link power down.
+ *
+ * The list of available policies and policy levels vary between SOCs. They can
+ * be viewed under pm_policy node directory. If SOC doesn't support any policy,
+ * this node won't be available. The different policies supported will be
+ * available as separate nodes under pm_policy.
+ *
+ * cat /sys/bus/pci/devices/.../pm_policy/<policy_type>
+ *
+ * Reading the policy file shows the different levels supported. The level which
+ * is applied presently is denoted by * (asterisk). E.g.,
+ *
+ * .. code-block:: console
+ *
+ * cat /sys/bus/pci/devices/.../pm_policy/soc_pstate
+ * 0 : soc_pstate_default
+ * 1 : soc_pstate_0
+ * 2 : soc_pstate_1*
+ * 3 : soc_pstate_2
+ *
+ * cat /sys/bus/pci/devices/.../pm_policy/xgmi_plpd
+ * 0 : plpd_disallow
+ * 1 : plpd_default
+ * 2 : plpd_optimized*
+ *
+ * To apply a specific policy
+ *
+ * "echo <level> > /sys/bus/pci/devices/.../pm_policy/<policy_type>"
+ *
+ * For the levels listed in the example above, to select "plpd_optimized" for
+ * XGMI and "soc_pstate_2" for soc pstate policy -
+ *
+ * .. code-block:: console
+ *
+ * echo "2" > /sys/bus/pci/devices/.../pm_policy/xgmi_plpd
+ * echo "3" > /sys/bus/pci/devices/.../pm_policy/soc_pstate
+ *
+ */
static ssize_t amdgpu_get_pm_policy_attr(struct device *dev,
struct device_attribute *attr,
char *buf)
--
2.25.1
