https://bugzilla.kernel.org/show_bug.cgi?id=207693

--- Comment #2 from Jan Ziak (http://atom-symbol.net) (0xe2.0x9a.0x9b@gmail.com) --- (In reply to Alex Deucher from comment #1)

The vbios defines the clock frequencies and nominal voltages, not the driver. The voltage is changed dynamically at runtime based on frequency and power and individual board leakage so you will see slight variations at runtime depending on the board.

particlefire from Vulkan demos (https://github.com/SaschaWillems/Vulkan) is an app with a relatively high power consumption (higher power consumption than Aida64 GPU stability test). On my machine&display it has performance of about 1000 FPS in a maximized window. I let it run for about 20 minutes, during which I manipulated GPU's fan speed.

According to /usr/bin/sensors, the GPU's junction/hotspot critical temperature is 99°C. So I lowered the fan RPM to less than 1000 in order to achieve higher temperatures. Even when the hotspot temperature was 105°C (6°C above critical) and GPU edge temperature was 86°C it had no effect on the FPS of particlefire (still about 1000 FPS).

radeontop (https://github.com/clbr/radeontop) was showing 1885MHz all the time during the testing.

In summary, I am unable to confirm your claim that the GPU is self-adjusting its voltage or frequency in Linux.

If you know an alternative approach (other than the one described above) to verify that the GPU is dynamically changing voltage and frequency in Linux due to temperatures and power consumption, please let me know.