drm/doc: Add amdgpu hwmon/power documentation (v2)

Document the hwmon and power control interfaces exposed
by the amdgpu driver.

v2: use section rather than chapter for now
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Documentation/gpu/amdgpu.rst

@@ -61,3 +61,56 @@ Interrupt Handling
 
 .. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c
    :internal:
+
+GPU Power/Thermal Controls and Monitoring
+=========================================
+
+This section covers hwmon and power/thermal controls.
+
+HWMON Interfaces
+----------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+   :doc: hwmon
+
+GPU sysfs Power State Interfaces
+--------------------------------
+
+GPU power controls are exposed via sysfs files.
+
+power_dpm_state
+~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+   :doc: power_dpm_state
+
+power_dpm_force_performance_level
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+   :doc: power_dpm_force_performance_level
+
+pp_table
+~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+   :doc: pp_table
+
+pp_od_clk_voltage
+~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+   :doc: pp_od_clk_voltage
+
+pp_dpm_sclk pp_dpm_mclk pp_dpm_pcie
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+   :doc: pp_dpm_sclk pp_dpm_mclk pp_dpm_pcie
+
+pp_power_profile_mode
+~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+   :doc: pp_power_profile_mode
+

drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c

@@ -80,12 +80,15 @@ void amdgpu_pm_acpi_event_handler(struct amdgpu_device *adev)
 /**
  * DOC: power_dpm_state
  *
- * This is a legacy interface and is only provided for backwards compatibility.
- * The amdgpu driver provides a sysfs API for adjusting certain power
- * related parameters.  The file power_dpm_state is used for this.
+ * The power_dpm_state file is a legacy interface and is only provided for
+ * backwards compatibility. The amdgpu driver provides a sysfs API for adjusting
+ * certain power related parameters.  The file power_dpm_state is used for this.
  * It accepts the following arguments:
+ *
  * - battery
+ *
  * - balanced
+ *
  * - performance
  *
  * battery
@@ -169,14 +172,21 @@ static ssize_t amdgpu_set_dpm_state(struct device *dev,
  * The amdgpu driver provides a sysfs API for adjusting certain power
  * related parameters.  The file power_dpm_force_performance_level is
  * used for this.  It accepts the following arguments:
+ *
  * - auto
+ *
  * - low
+ *
  * - high
+ *
  * - manual
- * - GPU fan
+ *
  * - profile_standard
+ *
  * - profile_min_sclk
+ *
  * - profile_min_mclk
+ *
  * - profile_peak
  *
  * auto
@@ -463,8 +473,11 @@ static ssize_t amdgpu_set_pp_table(struct device *dev,
  * this.
  *
  * Reading the file will display:
+ *
  * - a list of engine clock levels and voltages labeled OD_SCLK
+ *
  * - a list of memory clock levels and voltages labeled OD_MCLK
+ *
  * - a list of valid ranges for sclk, mclk, and voltage labeled OD_RANGE
  *
  * To manually adjust these settings, first select manual using
@@ -1285,35 +1298,51 @@ static ssize_t amdgpu_hwmon_set_power_cap(struct device *dev,
  * DOC: hwmon
  *
  * The amdgpu driver exposes the following sensor interfaces:
+ *
  * - GPU temperature (via the on-die sensor)
+ *
  * - GPU voltage
+ *
  * - Northbridge voltage (APUs only)
+ *
  * - GPU power
+ *
  * - GPU fan
  *
  * hwmon interfaces for GPU temperature:
+ *
  * - temp1_input: the on die GPU temperature in millidegrees Celsius
+ *
  * - temp1_crit: temperature critical max value in millidegrees Celsius
+ *
  * - temp1_crit_hyst: temperature hysteresis for critical limit in millidegrees Celsius
  *
  * hwmon interfaces for GPU voltage:
+ *
  * - in0_input: the voltage on the GPU in millivolts
+ *
  * - in1_input: the voltage on the Northbridge in millivolts
  *
  * hwmon interfaces for GPU power:
+ *
  * - power1_average: average power used by the GPU in microWatts
+ *
  * - power1_cap_min: minimum cap supported in microWatts
+ *
  * - power1_cap_max: maximum cap supported in microWatts
+ *
  * - power1_cap: selected power cap in microWatts
  *
  * hwmon interfaces for GPU fan:
+ *
  * - pwm1: pulse width modulation fan level (0-255)
- * - pwm1_enable: pulse width modulation fan control method
- *                0: no fan speed control
- *                1: manual fan speed control using pwm interface
- *                2: automatic fan speed control
+ *
+ * - pwm1_enable: pulse width modulation fan control method (0: no fan speed control, 1: manual fan speed control using pwm interface, 2: automatic fan speed control)
+ *
  * - pwm1_min: pulse width modulation fan control minimum level (0)
+ *
  * - pwm1_max: pulse width modulation fan control maximum level (255)
+ *
  * - fan1_input: fan speed in RPM
  *
  * You can use hwmon tools like sensors to view this information on your system.