GPU Voltage Control Support Coming To AMDGPU Driver

Patches are being prepped to improve the OverDrive overclocking/underclocking support within the AMDGPU DRM driver and for allowing voltage controls.

Rex Zhu of the AMD Linux driver development team has sent out a new set of OverDrive clock/voltage patches for the AMDGPU Direct Rendering Manager kernel driver.

The work includes manual DPM (Dynamic Power Management) control for Sea Islands and Volcanic Islands being added to AMDGPU, and rolling out a new pp_od_clk_voltage sysfs entry.

The pp_od_clk_voltage sysfs interface allows overriding the core and memory clock speeds and associated voltage steppings. Here's an example:

OD_SCLK:
0: 300Mhz 800 mV
1: 466Mhz 818 mV
2: 751Mhz 824 mV
3: 1019Mhz 987 mV
4: 1074Mhz 1037 mV
5: 1126Mhz 1087 mV
6: 1169Mhz 1137 mV
7: 1206Mhz 1150 mV
OD_MCLK:
0: 300Mhz 800 mV
1: 1650Mhz 1000 mV

But it doesn't appear possible at this time to under/over-volt the GPU without changing the frequency.

These current patches can be found on amd-gfx. The patches are too late to land for Linux 4.16 but hopefully for Linux 4.17 we'll see this work land along with other OverDrive improvements.