Add 'Radeon Temperature'

Radeon-Temperature.md

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+## Overview
+
+When using a laptop with ATI/AMD GPU as a mini-server, the defaults for the `radeon` kernel module are set to a balanced mode for typical use. However, this causes the GPU to produce slighly more heat, which then triggers the SMBIOS fan controls to cool it.
+
+Install the `lm-sensors` package (depending on Linux distro, the package has different names - `lm_sensors`, `sensors`, etc.) and use the `sensors` command to view the temperatures and fans when implementing the below configurations.
+
+
+## Configuration
+
+Reboot after adding the below.
+
+These settings ensure DPM/ASPM (power management) are enabled when the radeon kernel module loads, and disables the TV/Audio features we don't need.
+
+**/etc/modprobe.d/radeon.conf**
+```
+options radeon dpm=1 aspm=1 tv=0 audio=0
+```
+
+These rules activate the DPM "battery" power state and sets the Performance mode to "low" when the kernel module loads and detects the hardware.
+
+**/etc/udev/rules.d/30-radeon-pm.rules**
+```
+SUBSYSTEM=="drm", DRIVERS=="radeon", ATTR{device/power_dpm_state}="battery"
+SUBSYSTEM=="drm", DRIVERS=="radeon", ATTR{device/power_dpm_force_performance_level}="low"
+```
+
+## Status Check
+
+Helper script, nothing fancy.
+
+**radcheck.sh**
+```
+#!/usr/bin/env bash
+
+_MOD="radeon"
+_HW="/sys/class/drm/card0"
+
+echo -e "\nModule:   ${_MOD}"
+echo -e "Hardware: ${_HW}\n"
+echo -n "DPM enabled:   "; cat /sys/module/${_MOD}/parameters/dpm
+echo -n "ASPM enabled:  "; cat /sys/module/${_MOD}/parameters/aspm
+echo -n "TV enabled:    "; cat /sys/module/${_MOD}/parameters/tv
+echo -n "Audio enabled: "; cat /sys/module/${_MOD}/parameters/audio
+echo -n "DPM perfstate: "; cat ${_HW}/device/power_dpm_state
+echo -n "DPM perfmode:  "; cat ${_HW}/device/power_dpm_force_performance_level
+echo
+sensors | egrep "(CPU|GPU|Fan):"
+```