Messages in this thread | | | Date | Thu, 20 Jun 2013 17:01:22 -0700 | From | Sören Brinkmann <> | Subject | clocksource with changing frequency? |
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Hi all,
I have a question/problem with a clocksource whose input frequency can change. On Zynq we use the cadece_ttc timer as clocksource. Its input clock is tightly coupled to the CPU clock. I.e. it changes when cpufreq scales the CPU clocks. To compensate this, I added a clock notifier doing this on a frequency change: clocksource_unregister(&ttccs->cs); clocksource_register_hz(&ttccs->cs, ndata->new_rate / PRESCALE);
This just seems not to be the most elegant way, a heavy weight operation and results in a couple of locking errors in combination with suspend/hotplug.
Is there a sane solution for such a case? E.g. for clockevent devices there is a 'clockevents_update_freq()' to adjust to changing frequencies.
I assume the sanest solution is an external oscillator as clock input, but I think our platforms don't provide that :(
Thanks, Sören
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