improve cx_lowest logic

[Kevin Oberman]

On Wed, Sep 5, 2012 at 9:32 AM, Andriy Gapon <avg at freebsd.org> wrote:
> on 05/09/2012 19:23 Kevin Oberman said the following:
>> On Wed, Sep 5, 2012 at 9:12 AM, Andriy Gapon <avg at freebsd.org> wrote:
>>> on 05/09/2012 18:17 Kevin Oberman said the following:
>>>> Thanks so much! This should finally make Cx states work on my
>>>> ThinkPad! I really appreciate it. Guess it's time to do my weekly
>>>> upgrade of this system.
>>>
>>> I haven't sneaked in that other commit :-(
>>
>> Oops! :-(
>>
>> Oh, well. At least it should make it to /base/stable/9 soon. Right???
>> (I only run release/ or releng/ or for an occasional test.)
>>
>
> It's already in stable/9 :)

Ahh! I now see C3/109, but I see some strange behavior. When on AC
power, only C1/1 and C2/104 are available, but cx_lowest is C3, even
though C3 is not available. If I switch to battery, C1/1, C2/80 and
C3/109 are available (???), but cx_lowest is set to C2. I find the Cx
value sets a bit odd, but the setting of cx_lowest appears to be a
bug, at least to me. I can manually set cx_lowest to C3 and I actually
use C3.

My suspicion is that there is either a race or a logic issue where
x_lowest is reset to the lowest value before the available Cx values
are set, so cx_lowest is always set the the lowest Cx state from the
previous power configuration. (This is a guess, but it fits what I am
seeing very well.)
-- 
R. Kevin Oberman, Network Engineer
E-mail: kob6558 at gmail.com