On Tue, 1 Sep 2015 11:32:36 +0530
Viresh Kumar [off-list ref] wrote:

On 01-09-15, 13:36, vichy wrote:

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I try to call below 2 functions to change the frequency of clocksource
and clockevent, but the above b) sleep time is still incorrect when
cpu runs in 500Mhz.
    clockevents_update_freq(this_cpu_ptr(gt_evt), gt_clk_rate);
    __clocksource_updatefreq_hz(&gt_clocksource, gt_clk_rate);

How and when were you calling them? What kernel version is it ?

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Clock Event Device: arm_global_timer

This driver doesn't have support to update clkevt device's freq. You
may need to modify that based on how arch/arm/kernel/smp_twd.c is
updated. look for: clockevents_update_freq().

This can only help the clockevent. Even with this cpufreq notifier
update, the globaltimer clocksource still can't hold correct/accurate time.

I think the arm global timer is not suitable for clocksource if cpufreq is
enabled.