Messages in this thread | | | Date | Tue, 29 Nov 2016 14:42:11 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] clocksource/arm_global_timer: reconfigure clockevents after cpufreq change |
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On Tue, 29 Nov 2016, Alexander Kochetkov wrote:
> After a cpufreq transition, update the clockevent's frequency > by fetching the new clock rate from the clock framework and > reprogram the next clock event.
The frequency change would not only affect the clockevent device, it also would affect the clocksource. So the patch is incomplete, but see below.
> The clock supplying the arm-global-timer on the rk3188 is coming > from the the cpu clock itself and thus changes its rate everytime > cpufreq adjusts the cpu frequency.
That's broken and the clk framework should keep the CORE_PERI clock at a constant rate by reprogramming the divider of the CPU clock.
> Found by code review, real impact not known. Assume what actual > HZ value will be different from expected on platforms using > arm-global-timer as clockevent.
Assumptions w/o real impact are a perfect reason not to apply that patch. This want's a proper proof that the global timer really changes and this hackery is required, which I seriously doubt.
Thanks,
tglx
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