[PATCH v5 10/10] Documentation/amdgpu: Add PM policy documentation

[Kamal, Asad]

[AMD Official Use Only - AMD Internal Distribution Only]


Series is

Reviewed-by: Asad Kamal <asad.kamal at amd.com<mailto:asad.kamal at amd.com>>



Thanks & Regards

Asad

From: Deucher, Alexander <Alexander.Deucher at amd.com>
Sent: Friday, May 17, 2024 12:57 AM
To: Lazar, Lijo <Lijo.Lazar at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Zhang, Hawking <Hawking.Zhang at amd.com>; Kamal, Asad <Asad.Kamal at amd.com>; Ma, Le <Le.Ma at amd.com>
Subject: Re: [PATCH v5 10/10] Documentation/amdgpu: Add PM policy documentation


[AMD Official Use Only - AMD Internal Distribution Only]

I didn't have time to go through every patch in detail, but overall it looks good to me.  The series is:
Acked-by: Alex Deucher <alexander.deucher at amd.com<mailto:alexander.deucher at amd.com>>
________________________________
From: Lazar, Lijo <Lijo.Lazar at amd.com<mailto:Lijo.Lazar at amd.com>>
Sent: Thursday, May 16, 2024 8:43 AM
To: amd-gfx at lists.freedesktop.org<mailto:amd-gfx at lists.freedesktop.org> <amd-gfx at lists.freedesktop.org<mailto:amd-gfx at lists.freedesktop.org>>
Cc: Zhang, Hawking <Hawking.Zhang at amd.com<mailto:Hawking.Zhang at amd.com>>; Deucher, Alexander <Alexander.Deucher at amd.com<mailto:Alexander.Deucher at amd.com>>; Kamal, Asad <Asad.Kamal at amd.com<mailto:Asad.Kamal at amd.com>>; Ma, Le <Le.Ma at amd.com<mailto:Le.Ma at amd.com>>
Subject: [PATCH v5 10/10] Documentation/amdgpu: Add PM policy documentation

Add documentation about the newly added pm_policy node in sysfs.

Signed-off-by: Lijo Lazar <lijo.lazar at amd.com<mailto:lijo.lazar at amd.com>>
---

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
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