Thanks.
I will try to add more layman terms here to map cooling state with
frequencies. So, the cooling state 0 maps to the highest frequency the
cpufreq table supports, and the highest cooling state n maps to the
lowest frequency. Right ?
On 30-07-15, 13:21, Radivoje Jovanovic wrote:
> In this case both userspace thermal solution and cpu_cooling are
> changing policy->max and the userspace solution will let governor or HW
> (depends on architecture) decide the clipped-freq. Now let us say that
> cpu_cooling has 4 available states 0-3
Lets say: 0 == 1.2 GHz
1 == 1.1 GHz
2 == 1 GHz
3 == 800 MHz
> and let us say that cpu_cooling
> has set the state 1 as the last state.
i.e. cpu_cooling says "don't go over 1.1 GHz"..
> Now userspace component comes in
> and changes the state of the system that matches cpu_cooling state 0.
So, policy->max reaches 1.2 GHz and that is not in sync with
cpu_cooling. Right ?
> cpu_cooling is unaware of this change and does not change the local
> cur_state.
That's where I think you one of us might be incorrect. At this point
when policy->max is changed to 1.2 GHz, a notifier will get issued to
cpu_cooling, which will bring policy->max again to 1.1 GHz and so
things will be back in control.
> Now the temperature changes and cpu_cooling should change
> the system state to 1 (userspace component malfunctioned and is not
> picking up this change) but since the cur_state is already at 1
> cpu_cooling will not do anything since it believes it is in the correct
> state. Hope this explains it better
--
viresh
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