[Bug 292615] cpufreq changes causes AMD 4750U to run 11x slower

From: <bugzilla-noreply_at_freebsd.org>
Date: Tue, 20 Jan 2026 18:30:50 UTC 
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292615

            Bug ID: 292615
           Summary: cpufreq changes causes AMD 4750U to run 11x slower
           Product: Base System
           Version: 16.0-CURRENT
          Hardware: amd64
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: cracauer@cons.org

Commit to cpufreq 3e6e4e4a0d42fa24f3b2a1c087e9ad25f9594081 "hwpstate: add CPPC
support for pstate driver on AMD"

causes my laptop to run at 399 MHz, about 11 times slower than before the
commit.

It is a Thinkpad T1 gen 1 AMD Ryzen 7 PRO 4750U with Radeon Graphics
(1696.91-MHz K8-class CPU).                                                     

Dmesg from a kernel before that commit:
https://www.cons.org/goodkernel.dmesg

Dmesg from a kernel after that commit:
https://www.cons.org/badkernel.dmesg

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