From da4e4f18afe0f3729d68f3785c5802f786d36e34 Mon Sep 17 00:00:00 2001 From: Lorenzo Pieralisi Date: Tue, 23 Feb 2016 18:22:39 +0000 Subject: 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 Cc: Sudeep Holla Cc: Daniel Lezcano Cc: Mathieu Poirier Cc: Mark Rutland Acked-by: Ashwin Chaugule Acked-by: Kevin Hilman Signed-off-by: Lorenzo Pieralisi Signed-off-by: Will Deacon --- include/linux/perf/arm_pmu.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/perf') diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 2d5eaaa90078..4196c90a3c88 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -108,6 +108,7 @@ struct arm_pmu { struct platform_device *plat_device; struct pmu_hw_events __percpu *hw_events; struct notifier_block hotplug_nb; + struct notifier_block cpu_pm_nb; }; #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu)) -- cgit v1.2.3