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8b9951ed7e
CPU_PM_CPU_IDLE_ENTER_RETENTION skips calling cpu_pm_enter() and cpu_pm_exit(). By not calling cpu_pm functions in idle entry/exit paths we can reduce the latency involved in entering and exiting the low power idle state. On ARM64 based Qualcomm server platform we measured below overhead for calling cpu_pm_enter and cpu_pm_exit for retention states. workload: stress --hdd #CPUs --hdd-bytes 32M -t 30 Average overhead of cpu_pm_enter - 1.2us Average overhead of cpu_pm_exit - 3.1us Acked-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
66 lines
1.5 KiB
C
66 lines
1.5 KiB
C
/*
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* ARM64 CPU idle arch support
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*
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* Copyright (C) 2014 ARM Ltd.
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* Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/acpi.h>
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#include <linux/cpuidle.h>
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#include <linux/cpu_pm.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <asm/cpuidle.h>
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#include <asm/cpu_ops.h>
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int arm_cpuidle_init(unsigned int cpu)
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{
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int ret = -EOPNOTSUPP;
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if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_suspend &&
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cpu_ops[cpu]->cpu_init_idle)
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ret = cpu_ops[cpu]->cpu_init_idle(cpu);
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return ret;
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}
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/**
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* arm_cpuidle_suspend() - function to enter a low-power idle state
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* @arg: argument to pass to CPU suspend operations
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*
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* Return: 0 on success, -EOPNOTSUPP if CPU suspend hook not initialized, CPU
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* operations back-end error code otherwise.
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*/
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int arm_cpuidle_suspend(int index)
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{
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int cpu = smp_processor_id();
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return cpu_ops[cpu]->cpu_suspend(index);
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}
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#ifdef CONFIG_ACPI
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#include <acpi/processor.h>
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#define ARM64_LPI_IS_RETENTION_STATE(arch_flags) (!(arch_flags))
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int acpi_processor_ffh_lpi_probe(unsigned int cpu)
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{
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return arm_cpuidle_init(cpu);
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}
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int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
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{
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if (ARM64_LPI_IS_RETENTION_STATE(lpi->arch_flags))
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return CPU_PM_CPU_IDLE_ENTER_RETENTION(arm_cpuidle_suspend,
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lpi->index);
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else
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return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, lpi->index);
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}
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#endif
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