Linux 6.10 AMD P-State To Deliver Fixes, Better Support On Older Zen CPUs

The recent AMD P-State Linux driver patches for heterogeneous core CPU topology, Fast CPPC, and Core Performance Boost haven't made it to the Linux power management's "-next" branch ahead of the imminent Linux 6.10 cycle. Thus it looks like those features won't be ready to make it for v6.10 unless by chance being deemed ready in the coming days and then sent in as part of a secondary set of merge window changes. However, some other AMD P-State fixes/improvements are queued up.

For the AMD P-State CPU frequency scaling driver in Linux 6.10, queued up earlier this month were the driver updates:

"- Enable CPPC v2 for certain processors in the family 17H, as requested by TR40 processor users who expect improved performance and lower system temperature.

- Change latency and delay values to be read from platform firmware firstly for more accurate timing.

- A new quirk is introduced for supporting amd-pstate on legacy processors which either lack CPPC capability, or only only have CPPC v2 capability."

Those changes are ready to go for AMD P-State in Linux 6.10.

Plus this patch was queued in at the end of this week. This fixes an issue with the highest frequency state could limit the performance:

"To address the performance drop issue, an optimization has been implemented. The incorrect highest performance value previously set by the low-level power firmware for AMD CPUs with Family ID 0x19 and Model ID ranging from 0x70 to 0x7F series has been identified as the cause.

To resolve this, a check has been implemented to accurately determine the CPU family and model ID. The correct highest performance value is now set and the performance drop caused by the incorrect highest performance value are eliminated.

Before the fix, the highest frequency was set to 4200MHz, now it is set to 4971MHz which is correct."

This was a regression with Linux 6.9 for some hardware when introducing the AMD P-State Preferred Core support.