Lorenzo Pieralisi da4e4f18af drivers/perf: arm_pmu: implement CPU_PM notifier ... When a CPU is suspended (either through suspend-to-RAM or CPUidle), its PMU registers content can be lost, which means that counters registers values that were initialized on power down entry have to be reprogrammed on power-up to make sure the counters set-up is preserved (ie on power-up registers take the reset values on Cold or Warm reset, which can be architecturally UNKNOWN). To guarantee seamless profiling conditions across a core power down this patch adds a CPU PM notifier to ARM pmus, that upon CPU PM entry/exit from low-power states saves/restores the pmu registers set-up (by using the ARM perf API), so that the power-down/up cycle does not affect the perf behaviour (apart from a black-out period between power-up/down CPU PM notifications that is unavoidable). Cc: Will Deacon <will.deacon@arm.com> Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Acked-by: Kevin Hilman <khilman@baylibre.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>		2016-02-26 14:37:06 +00:00
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arm_pmu.h	drivers/perf: arm_pmu: implement CPU_PM notifier	2016-02-26 14:37:06 +00:00