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c324f43aed
Since commit45f1ff59e2("cpuidle: Return nohz hint from cpuidle_select()") Exynos CPUidle driver stopped entering C1 (AFTR) mode on Exynos4412-based Trats2 board. Further analysis revealed that the CPUidle framework changed the way it handles predicted timer ticks and reported target residency for the given idle states. As a result, the C1 (AFTR) state was not chosen anymore on completely idle device. The main issue was to high target residency value. The similar C1 (AFTR) state for 'coupled' CPUidle version used 10 times lower value for the target residency, despite the fact that it is the same state from the hardware perspective. The 100000us value for standard C1 (AFTR) mode is there from the begining of the support for this idle state, added by the commit67173ca492("ARM: EXYNOS: Add support AFTR mode on EXYNOS4210"). That commit doesn't give any reason for it, instead it looks like it was blindly copied from the WFI/IDLE state of the same driver that time. That time, that value was probably not really used by the framework for any critical decision, so it didn't matter that much. Now it turned out to be an issue, so unify the target residency with the 'coupled' version, as it seems to better match the real use case values and restores the operation of the Exynos CPUidle driver on the idle device. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
147 lines
3.4 KiB
C
147 lines
3.4 KiB
C
/*
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* Copyright (c) 2011-2014 Samsung Electronics Co., Ltd.
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* http://www.samsung.com
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*
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* Coupled cpuidle support based on the work of:
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* Colin Cross <ccross@android.com>
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* Daniel Lezcano <daniel.lezcano@linaro.org>
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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/cpuidle.h>
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#include <linux/cpu_pm.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/of.h>
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#include <linux/platform_data/cpuidle-exynos.h>
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#include <asm/suspend.h>
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#include <asm/cpuidle.h>
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static atomic_t exynos_idle_barrier;
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static struct cpuidle_exynos_data *exynos_cpuidle_pdata;
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static void (*exynos_enter_aftr)(void);
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static int exynos_enter_coupled_lowpower(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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int ret;
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exynos_cpuidle_pdata->pre_enter_aftr();
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/*
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* Waiting all cpus to reach this point at the same moment
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*/
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cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
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/*
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* Both cpus will reach this point at the same time
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*/
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ret = dev->cpu ? exynos_cpuidle_pdata->cpu1_powerdown()
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: exynos_cpuidle_pdata->cpu0_enter_aftr();
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if (ret)
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index = ret;
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/*
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* Waiting all cpus to finish the power sequence before going further
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*/
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cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
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exynos_cpuidle_pdata->post_enter_aftr();
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return index;
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}
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static int exynos_enter_lowpower(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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int new_index = index;
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/* AFTR can only be entered when cores other than CPU0 are offline */
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if (num_online_cpus() > 1 || dev->cpu != 0)
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new_index = drv->safe_state_index;
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if (new_index == 0)
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return arm_cpuidle_simple_enter(dev, drv, new_index);
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exynos_enter_aftr();
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return new_index;
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}
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static struct cpuidle_driver exynos_idle_driver = {
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.name = "exynos_idle",
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.owner = THIS_MODULE,
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.states = {
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[0] = ARM_CPUIDLE_WFI_STATE,
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[1] = {
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.enter = exynos_enter_lowpower,
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.exit_latency = 300,
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.target_residency = 10000,
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.name = "C1",
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.desc = "ARM power down",
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},
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},
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.state_count = 2,
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.safe_state_index = 0,
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};
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static struct cpuidle_driver exynos_coupled_idle_driver = {
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.name = "exynos_coupled_idle",
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.owner = THIS_MODULE,
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.states = {
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[0] = ARM_CPUIDLE_WFI_STATE,
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[1] = {
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.enter = exynos_enter_coupled_lowpower,
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.exit_latency = 5000,
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.target_residency = 10000,
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.flags = CPUIDLE_FLAG_COUPLED |
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CPUIDLE_FLAG_TIMER_STOP,
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.name = "C1",
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.desc = "ARM power down",
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},
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},
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.state_count = 2,
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.safe_state_index = 0,
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};
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static int exynos_cpuidle_probe(struct platform_device *pdev)
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{
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int ret;
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if (IS_ENABLED(CONFIG_SMP) &&
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(of_machine_is_compatible("samsung,exynos4210") ||
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of_machine_is_compatible("samsung,exynos3250"))) {
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exynos_cpuidle_pdata = pdev->dev.platform_data;
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ret = cpuidle_register(&exynos_coupled_idle_driver,
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cpu_possible_mask);
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} else {
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exynos_enter_aftr = (void *)(pdev->dev.platform_data);
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ret = cpuidle_register(&exynos_idle_driver, NULL);
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}
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if (ret) {
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dev_err(&pdev->dev, "failed to register cpuidle driver\n");
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return ret;
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}
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return 0;
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}
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static struct platform_driver exynos_cpuidle_driver = {
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.probe = exynos_cpuidle_probe,
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.driver = {
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.name = "exynos_cpuidle",
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},
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};
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builtin_platform_driver(exynos_cpuidle_driver);
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