These are specified by ATOM_VOLTAGE_OBJECT structure in VOLTAGE_OBJECT_INFO table, so I guess the driver does initialization from VBIOS on startup and then keeps the values as initialized. It's not possible to change these via PowerPlay as it's a different table, but it would be possible to add access to them via sysfs I think.

I already started working on adding interface to read GPU load, consumption, etc, so these would be just additions to it. What I don't like on this is that the amdgpu driver crashes when I try to unload it, so when I compile a new version I have to reboot the machine, which is kinda annoying.

I would check accessing these registers tomorrow

If you mean if it's possible to change  the `VDDCOffset` in SCLKDependencyTable then yeah it is, the question is if the AMDGPU driver would honor it, I think it won't.


So you can overwrite it through the script easily:


I would like to add a more automatic solution to do undervolting, but that would take some time to do properly. I looked at the amdgpu driver and I was not able to figure out if it's using the voltage offsets or not. It seems it has no effect, but I'm not completely sure.

I would like to announce a new project for tweaking AMDGPUs on Linux. It's an open-source solution for people that would like to write their own scripts. It uses node.js and has a library part and script part.

https://github.com/kobalicek/amdtweak

It's unfinished project and I just released it as a preview. I would like to get some feedback before I start adding more features. I designed it as a library, but I would like to provide more scripts and problem solutions in the future.