Bug 109101

Summary: [A10-7800] CPU is capped to 3GHz if BAPM is enabled
Product: Drivers Reporter: Real Name (immarcescibilis)
Component: Video(DRI - non Intel)Assignee: drivers_video-dri
Status: NEW ---    
Severity: normal    
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 4.2.6 Subsystem:
Regression: No Bisected commit-id:

Description Real Name 2015-12-09 01:05:45 UTC 
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.
Comment 1 Real Name 2016-02-08 16:44:33 UTC 
Some news:

- Tested with the current stable kernel (4.4.1). Same issue.
- The turbo frequencies are reached only if I disable DPM (dpm=0) and enable BAPM, but then I lose GPU performance. It's either one or another, it seems.