cpufreq: suspend governors on system suspend/hibernate
This patch adds cpufreq suspend/resume calls to dpm_{suspend|resume}() for handling suspend/resume of cpufreq governors. Lan Tianyu (Intel) & Jinhyuk Choi (Broadcom) found an issue where the tunables configuration for clusters/sockets with non-boot CPUs was lost after system suspend/resume, as we were notifying governors with CPUFREQ_GOV_POLICY_EXIT on removal of the last CPU for that policy which caused the tunables memory to be freed. This is fixed by preventing any governor operations from being carried out between the device suspend and device resume stages of system suspend and resume, respectively. We could have added these callbacks at dpm_{suspend|resume}_noirq() level, but there is an additional problem that the majority of I/O devices is already suspended at that point and if cpufreq drivers want to change the frequency before suspending, then that not be possible on some platforms (which depend on peripherals like i2c, regulators, etc). Reported-and-tested-by: NLan Tianyu <tianyu.lan@intel.com> Reported-by: NJinhyuk Choi <jinchoi@broadcom.com> Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org> [rjw: Changelog] Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
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