problems getting AMD C-70 APU working with powerd/cpufreq

[tech-lists]

On Wed, Oct 18, 2017 at 12:42:42PM +0100, tech-lists wrote:
>On Tue, Oct 17, 2017 at 06:23:06PM -0400, Anthony Jenkins wrote:
>>cpufreq(4) does not support AMD processor family 0x14 (20), which I
>>believe your dmesg showed your processor to be.
>
>aha!
>
>>I had added support for controlling the frequency on some later AMD
>>families last year, but the AMD documentation for the 0x14 family is
>>pretty complicated for my tiny brain.  The other families control
>>processor frequency with a single register, but AFACT you use P-states
>>on family 0x14.  You can have up to 8 P-states, each of which specifies
>>a power/frequency configuration.  If someone could point me to a
>>reference for controlling the frequency for this family, I could submit
>>something for review...no idea what Linux does for this family.
>
>Would it help if I were to get hardware output from booting temporarily
>to linux mint?

[thought I'd try it anyway]

Linux info here:
https://www.zyxst.net/txt/amd-c70-netbook/linux-dmesg-amdc70.txt
https://www.zyxst.net/txt/amd-c70-netbook/linux-cpufreq-info-amdc70.txt

cpufreq appears to be working on linux. Because of this and that
brightness control works, I've installed linux mint permanently. If you
need me to, I can easily boot into freebsd to run tests; equally can run
tests from linux. I'd prefer to run freebsd, but the inability to turn
down screen brightness was a showstopper.

many thanks,
-- 
J.