Tosho, I had exactly the same problem about setting the power_profile at startup and keeping it thourgh supend-resume applying the common solutions (as described here) and finally found a working alternative solution using pm-utils. I'm not sure if it is the best way to do it (I'm new to Linux) but it does all I wished for: Set the radeon power_profile to low on boot and retain that setting after suspend-resume.

Step 1: Create hook

gksudo gedit /usr/lib/pm-utils/power.d/radeon-power_profile

Step 2: Fill in the desired setting

#!/bin/sh



echo profile > /sys/class/drm/card0/device/power_method

echo low > /sys/class/drm/card0/device/power_profile



exit 0

Step 3: Make it executable

sudo chmod +x /usr/lib/pm-utils/power.d/radeon-power_profile

That's it :)