On 11 September 2014 15:43, Shilpasri G Bhat
[off-list ref] wrote:

This patch ensures the cpus to kexec/reboot at nominal frequency.
Nominal frequency is the highest cpu frequency on PowerPC at
which the cores can run without getting throttled.

If the host kernel had set the cpus to a low pstate and then it
kexecs/reboots to a cpufreq disabled kernel it would cause the target
kernel to perform poorly. It will also increase the boot up time of
the target kernel. So set the cpus to high pstate, in this case to
nominal frequency before rebooting to avoid such scenarios.

The reboot notifier will set the cpus to nominal frequncy.

Signed-off-by: Shilpasri G Bhat <redacted>
Suggested-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Preeti U Murthy <redacted>
---
Changes v2->v3:
We return EBUSY when cpufreq governor tries to change the frequency
after rebooting is set to true. This results in console being flushed
with error messages indicating failed attempts to change the
frequency. So instead of returning EBUSY we return 0 to stop the
governor from changing the frequency without alerting a failure to
do the same on reboot, as this  is not an errorneaos condition.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>