[Bug 109101] New: [A10-7800] CPU is capped to 3GHz if BAPM is enabled

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=109101

            Bug ID: 109101
           Summary: [A10-7800] CPU is capped to 3GHz if BAPM is enabled
           Product: Drivers
           Version: 2.5
    Kernel Version: 4.2.6
          Hardware: x86-64
                OS: Linux
              Tree: Fedora
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Video(DRI - non Intel)
          Assignee: drivers_video-dri@kernel-bugs.osdl.org
          Reporter: immarcescibilis@outlook.com
        Regression: No

I have an A10-7800 APU with a 3.5GHz clock (3.9/3.8/3.6 turbo) on an MSI
A88XM-E45 board that doesn't seem to suffer from the lack of BAPM, since it was
disabled by default and I had to enable it manually, after doing some research
on how to enable TurboCore on Linux. The fact of the matter is not only that it
doesn't work at all, but that it caps the CPU clock to 3GHz even on full load.
If I disable BAPM, the clocks raise normally to 3.5GHz. In my tests, I've
noticed a couple of things:

- Cool'n'Quiet is irrelevant. BAPM throttles the CPU clock whether Cool'n'Quiet
is disabled or enabled;
- With BAPM enabled, both CPU and GPU temperatures rise together when on full
load, even if there's no GPU usage;
- The turbo frequencies are never reached.

I made all measurements with turbostat while running either POV-Ray or stress
--cpu.

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