smp_twd fix for adapting to cpu frequency change
shiraz hashim
shiraz.linux.kernel at gmail.com
Thu May 3 07:15:06 EDT 2012
Hi Linus,
In your following patch,
commit 4fd7f9b128107034fa925b6877fae3c275f0da86
Author: Linus Walleij <linus.walleij at linaro.org>
Date: Tue Dec 13 12:48:18 2011 +0100
ARM: 7212/1: smp_twd: reconfigure clockevents after cpufreq change
This break-out from Colin Cross' cpufreq-aware TWD patch
will handle the case when our localtimer's clock changes with
the cpu clock. A cpufreq transtion notifier will be registered
only if the platform has supplied a specified clock to the TWD.
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 necessary changes in the clockevents framework was done by
Thomas Gleixner in kernel v3.0.
When we handle twd_cpufreq_transition and reprogram the clock event,
the TWD_TIMER_LOAD register still contains the old load value
for CLOCK_EVT_MODE_PERIODIC case.
This results in wrong number of events generated per second.
Shouldn't we reprogram the TWD_TIMER_LOAD register to new
twd_timer_rate / HZ on frequency change as well ?
--
regards
Shiraz Hashim
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