power-profiles-daemon, the power mode settings backend in Gnome, released 0.20 today!
The new release added amdgpu panel power savings which uses dedicated hardware in systems with integrated Radeon graphics to decrease panel power consumption when the system is on battery.
This activates the DRM connector attribute panel_power_savings which takes a range from 0 to 4 to indicate how aggressively to enable panel power savings.
GNOME Power Mode settings page
