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Adept II

Kaveri iGPU P-State information is not documented in BIOS and Kernel Developer's Guide (BKDG)

I am working on a fork of AmdMsrTweaker on GitHub LogioTek/AmdMsrTweaker · GitHub  to try to add Kaveri iGPU P-State information/control but after scouring through BKDG I was unable to find any relevant DPM / P-State information for iGPU.

Does anyone know in what registers iGPU P-State / DPM information is located or can point me to the relevant documentation? It must be documented somewhere because programs like CPU-Z and GPU-Z provide some (but not all) relevant iGPU P-State information.

Can one of you AMD guys that monitoring this board reach out to one of your internal AMD sources knowledgeable about APUs for more information regarding this?

2 Replies

I'll ping the docs team - they don't hang around on the forum typically, but they might be able to come up with an answer.

Fingers crossed.


That would be much appreciated. For developers documentation is everything. I've been developing for non-x86 (Microchip, MIPS, ARM) embedded platforms for 10 years and now foraging into x86 for the first time. One big difference I noticed right away is lack of documentation and the hoops you have to jump through to get complete relevant documentation for x86, where as for other embedded platforms that I mentioned there is abundance of documentation (2000+ page main reference manual document with numerous other case specific application note documents), better forum support (both employees and peer developers), and availability of cheap development boards, not to mention those embedded platforms are much less complex than leading x86 SoCs so they are naturally easier for developers.

If AMD wants to succeed in embedded it's extremely important that documentation is on par with leading competing embedded platforms. AMD's current CEO, Lisa Su, is from Freescale and I am sure she understands all of this. There is progress already but there needs to be a lot more done for embedded at AMD in order for it to really be accessible to developers. There isn't even a section for embedded on this board.

P.S. While searching for Kaveri iGPU DPM P-State information I ran into another developer who needed the same information I am in search of and let me tell you he didn't waste any time, when he couldn't find what he needed, he just switched his development target from embedded Kaveri SKU to a Nvidia Tegra SKU where he was able to get the control that his application requires and never looked back. You can find out more about this incident and how it played out here: Some issues on BIOS and Kernel Developer’s Guide (BKDG)