| Message ID | 1306999978-4663-1-git-send-email-myungjoo.ham@samsung.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
> A system or a device may need to control suspend/wakeup events. It may > want to wakeup the system after a predefined amount of time or at a > predefined event decided while entering suspend for polling or delayed > work. Then, it may want to enter suspend again if its predefined wakeup > condition is the only wakeup reason and there is no outstanding events; > thus, it does not wakeup the userspace unnecessary or unnecessary > devices and keeps suspended as long as possible (saving the power). > > Enabling a system to wakeup after a specified time can be easily > achieved by using RTC. However, to enter suspend again immediately > without invoking userland and unrelated devices, we need additional > features in the suspend framework. > > Such need comes from: > > 1. Monitoring a critical device status without interrupts that can > wakeup the system. (in-suspend polling) > An example is ambient temperature monitoring that needs to shut down > the system or a specific device function if it is too hot or cold. The > temperature of a specific device may be needed to be monitored as well; > e.g., a charger monitors battery temperature in order to stop charging > if overheated. > > 2. Execute critical "delayed work" at suspend. > A driver or a system/board may have a delayed work (or any similar > things) that it wants to execute at the requested time. > For example, some chargers want to check the battery voltage some > time (e.g., 30 seconds) after the battery is fully charged and the > charger has stopped. Then, the charger restarts charging if the voltage > has dropped more than a threshold, which is smaller than "restart-charger" > voltage, which is a threshold to restart charging regardless of the > time passed. > > This patch allows to add "suspend_again" callback at struct > platform_suspend_ops and let the "suspend_again" callback return true if > the system is required to enter suspend again after the current instance > of wakeup. Device-wise suspend_again implemented at dev_pm_ops or > syscore is not done because: a) suspend_again feature is usually under > platform-wise decision and controls the behavior of the whole platform > and b) There are very limited devices related to the usage cases of > suspend_again; chargers and temperature sensors are mentioned so far. > > With suspend_again callback registered at struct platform_suspend_ops > suspend_ops in kernel/power/suspend.c with suspend_set_ops by the > platform, the suspend framework tries to enter suspend again by > looping suspend_enter() if suspend_again has returned true and there has > been no errors in the suspending sequence or pending wakeups (by > pm_wakeup_pending). > > Tested at Exynos4-NURI. > > Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com> > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> ACK.
On Thursday, June 02, 2011, MyungJoo Ham wrote: > A system or a device may need to control suspend/wakeup events. It may > want to wakeup the system after a predefined amount of time or at a > predefined event decided while entering suspend for polling or delayed > work. Then, it may want to enter suspend again if its predefined wakeup > condition is the only wakeup reason and there is no outstanding events; > thus, it does not wakeup the userspace unnecessary or unnecessary > devices and keeps suspended as long as possible (saving the power). > > Enabling a system to wakeup after a specified time can be easily > achieved by using RTC. However, to enter suspend again immediately > without invoking userland and unrelated devices, we need additional > features in the suspend framework. > > Such need comes from: > > 1. Monitoring a critical device status without interrupts that can > wakeup the system. (in-suspend polling) > An example is ambient temperature monitoring that needs to shut down > the system or a specific device function if it is too hot or cold. The > temperature of a specific device may be needed to be monitored as well; > e.g., a charger monitors battery temperature in order to stop charging > if overheated. > > 2. Execute critical "delayed work" at suspend. > A driver or a system/board may have a delayed work (or any similar > things) that it wants to execute at the requested time. > For example, some chargers want to check the battery voltage some > time (e.g., 30 seconds) after the battery is fully charged and the > charger has stopped. Then, the charger restarts charging if the voltage > has dropped more than a threshold, which is smaller than "restart-charger" > voltage, which is a threshold to restart charging regardless of the > time passed. > > This patch allows to add "suspend_again" callback at struct > platform_suspend_ops and let the "suspend_again" callback return true if > the system is required to enter suspend again after the current instance > of wakeup. Device-wise suspend_again implemented at dev_pm_ops or > syscore is not done because: a) suspend_again feature is usually under > platform-wise decision and controls the behavior of the whole platform > and b) There are very limited devices related to the usage cases of > suspend_again; chargers and temperature sensors are mentioned so far. > > With suspend_again callback registered at struct platform_suspend_ops > suspend_ops in kernel/power/suspend.c with suspend_set_ops by the > platform, the suspend framework tries to enter suspend again by > looping suspend_enter() if suspend_again has returned true and there has > been no errors in the suspending sequence or pending wakeups (by > pm_wakeup_pending). > > Tested at Exynos4-NURI. > > Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com> > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> OK, I'll queue it up for 3.1, but I'm still not sure if executing all of the .suspend_noirq() and .resume_noirq() callbacks in each iteration of the loop is optimal. Arguably, we can't do anything more fine grained at the moment, but that's something to think of in the future. > -- > Thank you for your valuable comments, Pavel, Rafael, Greg, and others. > > Changed from v4: > - rebased on Linux 3.0 rc1 > - removed partial_suspend/resume because they are not needed, for now. > Changed from v3: > - renamed local variable "pm_wkup_pending" to "wakeup_pending". > pm_wakeup_pending is not used because there is a function with the > same name. > Changed from v2: > - moved (again) from dev_pm_ops to suspend_ops > - settled suspend_again point at around suspend_enter(). > Changes from v1: > - moved from syscore to dev_pm_ops > - added generic ops for subsystems. > - cleaned up suspend_again code at kernel/power/suspend. > --- > include/linux/suspend.h | 8 ++++++++ > kernel/power/suspend.c | 13 ++++++++++--- > 2 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/include/linux/suspend.h b/include/linux/suspend.h > index 083ffea..e1e3742 100644 > --- a/include/linux/suspend.h > +++ b/include/linux/suspend.h > @@ -92,6 +92,13 @@ typedef int __bitwise suspend_state_t; > * @enter() and @wake(), even if any of them fails. It is executed after > * a failing @prepare. > * > + * @suspend_again: Returns whether the system should suspend again (true) or > + * not (false). If the platform wants to poll sensors or execute some > + * code during suspended without invoking userspace and most of devices, > + * suspend_again callback is the place assuming that periodic-wakeup or > + * alarm-wakeup is already setup. This allows to execute some codes while > + * being kept suspended in the view of userland and devices. > + * > * @end: Called by the PM core right after resuming devices, to indicate to > * the platform that the system has returned to the working state or > * the transition to the sleep state has been aborted. > @@ -113,6 +120,7 @@ struct platform_suspend_ops { > int (*enter)(suspend_state_t state); > void (*wake)(void); > void (*finish)(void); > + bool (*suspend_again)(void); > void (*end)(void); > void (*recover)(void); > }; > diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c > index 1c41ba2..d8a6c51 100644 > --- a/kernel/power/suspend.c > +++ b/kernel/power/suspend.c > @@ -128,10 +128,12 @@ void __attribute__ ((weak)) arch_suspend_enable_irqs(void) > /** > * suspend_enter - enter the desired system sleep state. > * @state: state to enter > + * @wakeup_pending: indicates that the power transition in progress > + * should be aborted. This should be just one line, otherwise kerneldoc will have problems with it. I'll fix it up. Thanks, Rafael
diff --git a/include/linux/suspend.h b/include/linux/suspend.h index 083ffea..e1e3742 100644 --- a/include/linux/suspend.h +++ b/include/linux/suspend.h @@ -92,6 +92,13 @@ typedef int __bitwise suspend_state_t; * @enter() and @wake(), even if any of them fails. It is executed after * a failing @prepare. * + * @suspend_again: Returns whether the system should suspend again (true) or + * not (false). If the platform wants to poll sensors or execute some + * code during suspended without invoking userspace and most of devices, + * suspend_again callback is the place assuming that periodic-wakeup or + * alarm-wakeup is already setup. This allows to execute some codes while + * being kept suspended in the view of userland and devices. + * * @end: Called by the PM core right after resuming devices, to indicate to * the platform that the system has returned to the working state or * the transition to the sleep state has been aborted. @@ -113,6 +120,7 @@ struct platform_suspend_ops { int (*enter)(suspend_state_t state); void (*wake)(void); void (*finish)(void); + bool (*suspend_again)(void); void (*end)(void); void (*recover)(void); }; diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 1c41ba2..d8a6c51 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -128,10 +128,12 @@ void __attribute__ ((weak)) arch_suspend_enable_irqs(void) /** * suspend_enter - enter the desired system sleep state. * @state: state to enter + * @wakeup_pending: indicates that the power transition in progress + * should be aborted. * * This function should be called after devices have been suspended. */ -static int suspend_enter(suspend_state_t state) +static int suspend_enter(suspend_state_t state, bool *wakeup_pending) { int error; @@ -165,7 +167,8 @@ static int suspend_enter(suspend_state_t state) error = syscore_suspend(); if (!error) { - if (!(suspend_test(TEST_CORE) || pm_wakeup_pending())) { + *wakeup_pending = pm_wakeup_pending(); + if (!(suspend_test(TEST_CORE) || *wakeup_pending)) { error = suspend_ops->enter(state); events_check_enabled = false; } @@ -199,6 +202,7 @@ static int suspend_enter(suspend_state_t state) int suspend_devices_and_enter(suspend_state_t state) { int error; + bool wakeup_pending = false; if (!suspend_ops) return -ENOSYS; @@ -220,7 +224,10 @@ int suspend_devices_and_enter(suspend_state_t state) if (suspend_test(TEST_DEVICES)) goto Recover_platform; - error = suspend_enter(state); + do { + error = suspend_enter(state, &wakeup_pending); + } while (suspend_ops->suspend_again && suspend_ops->suspend_again() && + !error && !wakeup_pending); Resume_devices: suspend_test_start();