![Zhang Rui](/assets/img/avatar_default.png)
PM_SUSPEND_FREEZE state is a general state that does not need any platform specific support, it equals frozen processes + suspended devices + idle processors. Compared with PM_SUSPEND_MEMORY, PM_SUSPEND_FREEZE saves less power because the system is still in a running state. PM_SUSPEND_FREEZE has less resume latency because it does not touch BIOS, and the processors are in idle state. Compared with RTPM/idle, PM_SUSPEND_FREEZE saves more power as 1. the processor has longer sleep time because processes are frozen. The deeper c-state the processor supports, more power saving we can get. 2. PM_SUSPEND_FREEZE uses system suspend code path, thus we can get more power saving from the devices that does not have good RTPM support. This state is useful for 1) platforms that do not have STR, or have a broken STR. 2) platforms that have an extremely low power idle state, which can be used to replace STR. The following describes how PM_SUSPEND_FREEZE state works. 1. echo freeze > /sys/power/state 2. the processes are frozen. 3. all the devices are suspended. 4. all the processors are blocked by a wait queue 5. all the processors idles and enters (Deep) c-state. 6. an interrupt fires. 7. a processor is woken up and handles the irq. 8. if it is a general event, a) the irq handler runs and quites. b) goto step 4. 9. if it is a real wake event, say, power button pressing, keyboard touch, mouse moving, a) the irq handler runs and activate the wakeup source b) wakeup_source_activate() notifies the wait queue. c) system starts resuming from PM_SUSPEND_FREEZE 10. all the devices are resumed. 11. all the processes are unfrozen. 12. system is back to working. Known Issue: The wakeup of this new PM_SUSPEND_FREEZE state may behave differently from the previous suspend state. Take ACPI platform for example, there are some GPEs that only enabled when the system is in sleep state, to wake the system backk from S3/S4. But we are not touching these GPEs during transition to PM_SUSPEND_FREEZE. This means we may lose some wake event. But on the other hand, as we do not disable all the Interrupts during PM_SUSPEND_FREEZE, we may get some extra "wakeup" Interrupts, that are not available for S3/S4. The patches has been tested on an old Sony laptop, and here are the results: Average Power: 1. RPTM/idle for half an hour: 14.8W, 12.6W, 14.1W, 12.5W, 14.4W, 13.2W, 12.9W 2. Freeze for half an hour: 11W, 10.4W, 9.4W, 11.3W 10.5W 3. RTPM/idle for three hours: 11.6W 4. Freeze for three hours: 10W 5. Suspend to Memory: 0.5~0.9W Average Resume Latency: 1. RTPM/idle with a black screen: (From pressing keyboard to screen back) Less than 0.2s 2. Freeze: (From pressing power button to screen back) 2.50s 3. Suspend to Memory: (From pressing power button to screen back) 4.33s >From the results, we can see that all the platforms should benefit from this patch, even if it does not have Low Power S0. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
373 lines
8.5 KiB
C
373 lines
8.5 KiB
C
/*
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* kernel/power/suspend.c - Suspend to RAM and standby functionality.
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*
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* Copyright (c) 2003 Patrick Mochel
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* Copyright (c) 2003 Open Source Development Lab
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* Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
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*
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* This file is released under the GPLv2.
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*/
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#include <linux/string.h>
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#include <linux/delay.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/cpu.h>
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#include <linux/syscalls.h>
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#include <linux/gfp.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/export.h>
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#include <linux/suspend.h>
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#include <linux/syscore_ops.h>
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#include <linux/ftrace.h>
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#include <trace/events/power.h>
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#include "power.h"
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const char *const pm_states[PM_SUSPEND_MAX] = {
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[PM_SUSPEND_FREEZE] = "freeze",
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[PM_SUSPEND_STANDBY] = "standby",
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[PM_SUSPEND_MEM] = "mem",
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};
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static const struct platform_suspend_ops *suspend_ops;
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static bool need_suspend_ops(suspend_state_t state)
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{
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return !!(state > PM_SUSPEND_FREEZE);
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}
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static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
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static bool suspend_freeze_wake;
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static void freeze_begin(void)
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{
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suspend_freeze_wake = false;
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}
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static void freeze_enter(void)
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{
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wait_event(suspend_freeze_wait_head, suspend_freeze_wake);
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}
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void freeze_wake(void)
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{
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suspend_freeze_wake = true;
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wake_up(&suspend_freeze_wait_head);
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}
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EXPORT_SYMBOL_GPL(freeze_wake);
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/**
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* suspend_set_ops - Set the global suspend method table.
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* @ops: Suspend operations to use.
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*/
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void suspend_set_ops(const struct platform_suspend_ops *ops)
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{
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lock_system_sleep();
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suspend_ops = ops;
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unlock_system_sleep();
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}
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EXPORT_SYMBOL_GPL(suspend_set_ops);
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bool valid_state(suspend_state_t state)
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{
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if (state == PM_SUSPEND_FREEZE)
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return true;
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/*
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* PM_SUSPEND_STANDBY and PM_SUSPEND_MEMORY states need lowlevel
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* support and need to be valid to the lowlevel
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* implementation, no valid callback implies that none are valid.
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*/
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return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
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}
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/**
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* suspend_valid_only_mem - Generic memory-only valid callback.
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*
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* Platform drivers that implement mem suspend only and only need to check for
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* that in their .valid() callback can use this instead of rolling their own
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* .valid() callback.
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*/
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int suspend_valid_only_mem(suspend_state_t state)
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{
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return state == PM_SUSPEND_MEM;
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}
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EXPORT_SYMBOL_GPL(suspend_valid_only_mem);
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static int suspend_test(int level)
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{
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#ifdef CONFIG_PM_DEBUG
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if (pm_test_level == level) {
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printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
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mdelay(5000);
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return 1;
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}
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#endif /* !CONFIG_PM_DEBUG */
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return 0;
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}
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/**
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* suspend_prepare - Prepare for entering system sleep state.
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*
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* Common code run for every system sleep state that can be entered (except for
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* hibernation). Run suspend notifiers, allocate the "suspend" console and
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* freeze processes.
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*/
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static int suspend_prepare(suspend_state_t state)
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{
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int error;
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if (need_suspend_ops(state) && (!suspend_ops || !suspend_ops->enter))
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return -EPERM;
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pm_prepare_console();
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error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);
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if (error)
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goto Finish;
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error = suspend_freeze_processes();
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if (!error)
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return 0;
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suspend_stats.failed_freeze++;
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dpm_save_failed_step(SUSPEND_FREEZE);
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Finish:
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pm_notifier_call_chain(PM_POST_SUSPEND);
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pm_restore_console();
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return error;
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}
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/* default implementation */
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void __attribute__ ((weak)) arch_suspend_disable_irqs(void)
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{
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local_irq_disable();
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}
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/* default implementation */
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void __attribute__ ((weak)) arch_suspend_enable_irqs(void)
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{
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local_irq_enable();
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}
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/**
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* suspend_enter - Make the system enter the given sleep state.
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* @state: System sleep state to enter.
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* @wakeup: Returns information that the sleep state should not be re-entered.
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*
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* This function should be called after devices have been suspended.
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*/
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static int suspend_enter(suspend_state_t state, bool *wakeup)
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{
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int error;
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if (need_suspend_ops(state) && suspend_ops->prepare) {
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error = suspend_ops->prepare();
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if (error)
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goto Platform_finish;
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}
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error = dpm_suspend_end(PMSG_SUSPEND);
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if (error) {
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printk(KERN_ERR "PM: Some devices failed to power down\n");
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goto Platform_finish;
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}
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if (need_suspend_ops(state) && suspend_ops->prepare_late) {
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error = suspend_ops->prepare_late();
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if (error)
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goto Platform_wake;
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}
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/*
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* PM_SUSPEND_FREEZE equals
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* frozen processes + suspended devices + idle processors.
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* Thus we should invoke freeze_enter() soon after
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* all the devices are suspended.
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*/
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if (state == PM_SUSPEND_FREEZE) {
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freeze_enter();
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goto Platform_wake;
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}
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if (suspend_test(TEST_PLATFORM))
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goto Platform_wake;
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error = disable_nonboot_cpus();
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if (error || suspend_test(TEST_CPUS))
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goto Enable_cpus;
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arch_suspend_disable_irqs();
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BUG_ON(!irqs_disabled());
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error = syscore_suspend();
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if (!error) {
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*wakeup = pm_wakeup_pending();
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if (!(suspend_test(TEST_CORE) || *wakeup)) {
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error = suspend_ops->enter(state);
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events_check_enabled = false;
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}
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syscore_resume();
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}
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arch_suspend_enable_irqs();
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BUG_ON(irqs_disabled());
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Enable_cpus:
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enable_nonboot_cpus();
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Platform_wake:
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if (need_suspend_ops(state) && suspend_ops->wake)
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suspend_ops->wake();
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dpm_resume_start(PMSG_RESUME);
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Platform_finish:
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if (need_suspend_ops(state) && suspend_ops->finish)
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suspend_ops->finish();
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return error;
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}
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/**
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* suspend_devices_and_enter - Suspend devices and enter system sleep state.
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* @state: System sleep state to enter.
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*/
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int suspend_devices_and_enter(suspend_state_t state)
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{
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int error;
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bool wakeup = false;
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if (need_suspend_ops(state) && !suspend_ops)
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return -ENOSYS;
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trace_machine_suspend(state);
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if (need_suspend_ops(state) && suspend_ops->begin) {
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error = suspend_ops->begin(state);
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if (error)
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goto Close;
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}
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suspend_console();
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ftrace_stop();
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suspend_test_start();
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error = dpm_suspend_start(PMSG_SUSPEND);
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if (error) {
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printk(KERN_ERR "PM: Some devices failed to suspend\n");
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goto Recover_platform;
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}
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suspend_test_finish("suspend devices");
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if (suspend_test(TEST_DEVICES))
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goto Recover_platform;
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do {
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error = suspend_enter(state, &wakeup);
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} while (!error && !wakeup && need_suspend_ops(state)
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&& suspend_ops->suspend_again && suspend_ops->suspend_again());
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Resume_devices:
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suspend_test_start();
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dpm_resume_end(PMSG_RESUME);
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suspend_test_finish("resume devices");
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ftrace_start();
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resume_console();
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Close:
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if (need_suspend_ops(state) && suspend_ops->end)
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suspend_ops->end();
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trace_machine_suspend(PWR_EVENT_EXIT);
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return error;
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Recover_platform:
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if (need_suspend_ops(state) && suspend_ops->recover)
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suspend_ops->recover();
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goto Resume_devices;
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}
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/**
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* suspend_finish - Clean up before finishing the suspend sequence.
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*
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* Call platform code to clean up, restart processes, and free the console that
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* we've allocated. This routine is not called for hibernation.
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*/
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static void suspend_finish(void)
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{
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suspend_thaw_processes();
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pm_notifier_call_chain(PM_POST_SUSPEND);
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pm_restore_console();
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}
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/**
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* enter_state - Do common work needed to enter system sleep state.
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* @state: System sleep state to enter.
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*
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* Make sure that no one else is trying to put the system into a sleep state.
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* Fail if that's not the case. Otherwise, prepare for system suspend, make the
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* system enter the given sleep state and clean up after wakeup.
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*/
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static int enter_state(suspend_state_t state)
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{
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int error;
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if (!valid_state(state))
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return -ENODEV;
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if (!mutex_trylock(&pm_mutex))
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return -EBUSY;
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if (state == PM_SUSPEND_FREEZE)
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freeze_begin();
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printk(KERN_INFO "PM: Syncing filesystems ... ");
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sys_sync();
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printk("done.\n");
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pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
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error = suspend_prepare(state);
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if (error)
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goto Unlock;
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if (suspend_test(TEST_FREEZER))
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goto Finish;
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pr_debug("PM: Entering %s sleep\n", pm_states[state]);
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pm_restrict_gfp_mask();
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error = suspend_devices_and_enter(state);
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pm_restore_gfp_mask();
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Finish:
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pr_debug("PM: Finishing wakeup.\n");
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suspend_finish();
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Unlock:
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mutex_unlock(&pm_mutex);
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return error;
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}
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/**
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* pm_suspend - Externally visible function for suspending the system.
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* @state: System sleep state to enter.
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*
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* Check if the value of @state represents one of the supported states,
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* execute enter_state() and update system suspend statistics.
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*/
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int pm_suspend(suspend_state_t state)
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{
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int error;
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if (state <= PM_SUSPEND_ON || state >= PM_SUSPEND_MAX)
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return -EINVAL;
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error = enter_state(state);
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if (error) {
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suspend_stats.fail++;
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dpm_save_failed_errno(error);
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} else {
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suspend_stats.success++;
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}
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return error;
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}
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EXPORT_SYMBOL(pm_suspend);
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