https://bugzilla.kernel.org/show_bug.cgi?id=81021

--- Comment #7 from LiNuxXer andre.d@gmx.net --- Hello Alex,

(In reply to Alex Deucher from comment #6)

Turbo Core (bapm) is controlled by a microcontroller on the APU. The same microcontroller also manages the GPU power management. On most APU systems, turbo core is enabled by default by the sbios, but apparently on your system it's not. Maybe there is a bios option to enable it by default on your system.

reconsidering everything you wrote and I thought I found out, I think I'll have to start from scratch.

Firstly, the BIOS does have Turbo Core and Cool'n'Quiet settings, along with many others. Also. it's the latest version, and the A10-6700 is not brand new.

Secondly, I noticed that even Ubuntu Server will install the radeon driver although there is no need to.

Thirdly, I made a quick test with a Gentoo installer (which neither loads the radeon module nor sets the ondemand governor) and an amperemeter (to be honest: two amperemeters, because I couldn't believe the results), and this completely confused me. While the system needs 96 W while in the BIOS, this drops to 56 W as soon as Linux boots. And I can't get a lower power consumption even if I set the ondemand governor, with the freq of the four cores shown to drop from 3700 to 1800. Several reviews mention a 35 W system (!) power consumption when the A10-6700 is idle, but in this setup, the changing frequency does not have the slightest effect (which it should even have with an average power supply).

I was wondering whether you could shed some additional light on this. How many settings actually influence this behaviour in total (since the BIOS also has "Cool'n'Qiet")? Is there any tool to display them? If not, would you help me to build one? Could we see some incomplete initialisation here? Is there any documentation on these settings? I'm groping in the dark here with no progress, and I may even have to exchange the HW if I don't get near the 35 W and have Turbo Core.

When the GPU driver loads and sets up the GPU power management, it can also enable or disable bapm. When bapm and GPU power mangement (dynamic GPU engine clock and voltage scaling, clock and powergating, etc.) are both enabled, some systems have stability problems (sudden reboots, hangs, graphical corruption, issues when switching between AC and battery).

I would be happy with some fixed low bandwidth setting for the graphics. Saw some indivation for 33 MHz during console mode but am not sure I can rely on this information.