There is an issue with the ACPI CPUFreq driver code has at times been less than ideal on recent AMD processors with delivering less than expected performance with being slow to ramp up to a higher performance state or otherwise coming up short of disabling the power management functionality outright.

AMD hasn't traditionally worked on the Linux CPU frequency scaling code as much as Intel does to their P-State scaling driver and other areas of power management AMD is ramping up efforts in these areas including around the Linux scheduler given their recent hiring spree while it now looks like thanks to the Steam Deck there is renewed interest in better optimising the CPU frequency scaling under Linux.

AMD and Valve have been working to improve the performance/power efficiency for modern AMD platforms running on Steam Play (Proton/ Wine) and have spearheaded "[The ACPI CPUFreq driver] was not very performance/power efficient for modern AMD platforms. A new CPU performance scaling design for AMD platform which has better performance per watt scaling on such as 3D game like Horizon Zero Dawn with VKD3D-Proton on Steam."

AMD will be showing off more about this at XDC. It's quite possible this new effort is focused on ACPI CPPC support with the previously proposed

Upstream kernel developers also voiced their preference to seeing AMD work to improve the generic ACPI CPPC CPUFreq driver code rather than having another vendor-specific solution. AMD has been working on better improvements around the now-default Schedutil governor for scheduler utilisation data in making CPU frequency scaling decisions.