[PATCH] ARM: smp_twd: Reconfigure clockevents after cpufreq change

Colin Cross ccross at android.com
Tue Jun 14 02:00:15 EDT 2011

On Mon, Jun 13, 2011 at 10:50 PM, Linus Walleij
<linus.ml.walleij at gmail.com> wrote:
> Colin, Per Fransson noted this:
>> From: Colin Cross <ccross at android.com>
>> +/*
>> + * Updates clockevent frequency when the cpu frequency changes.
>> + * Called on the cpu that is changing frequency with interrupts disabled.
>> + */
>> +static void twd_update_frequency(void *data)
>> +{
>> +       twd_timer_rate = clk_get_rate(twd_clk);
>> +
>> +       clockevents_update_freq(__get_cpu_var(twd_ce), twd_timer_rate);
>> +}
> Will only update the clockevent on the CPU where the cpufreq notifier
> gets called will it not? It's not called on each CPU AFAICT.
> So this function has to traverse all CPUs in twd_ce.

OMAP and Tegra both iterate through all the affected cpus in the
cpufreq driver and call cpufreq_notify_transtion once for each,
setting freqs.cpu to the target cpu.  The listener in the smp_twd
driver then bounces through smp_call_function_single to make sure it
is running on the affected cpu.  I believe that is the correct way to
handle multiple affected cpus.

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