kernel/linux.git/drivers/base/power/main.c, branch v4.4.296

PM: sleep: core: Fix the handling of pending runtime resume requests

2020-09-03T09:19:27+00:00

commit e3eb6e8fba65094328b8dca635d00de74ba75b45 upstream. It has been reported that system-wide suspend may be aborted in the absence of any wakeup events due to unforseen interactions of it with the runtume PM framework. One failing scenario is when there are multiple devices sharing an ACPI power resource and runtime-resume needs to be carried out for one of them during system-wide suspend (for example, because it needs to be reconfigured before the whole system goes to sleep). In that case, the runtime-resume of that device involves turning the ACPI power resource "on" which in turn causes runtime-resume requests to be queued up for all of the other devices sharing it. Those requests go to the runtime PM workqueue which is frozen during system-wide suspend, so they are not actually taken care of until the resume of the whole system, but the pm_runtime_barrier() call in __device_suspend() sees them and triggers system wakeup events for them which then cause the system-wide suspend to be aborted if wakeup source objects are in active use. Of course, the logic that leads to triggering those wakeup events is questionable in the first place, because clearly there are cases in which a pending runtime resume request for a device is not connected to any real wakeup events in any way (like the one above). Moreover, it is racy, because the device may be resuming already by the time the pm_runtime_barrier() runs and so if the driver doesn't take care of signaling the wakeup event as appropriate, it will be lost. However, if the driver does take care of that, the extra pm_wakeup_event() call in the core is redundant. Accordingly, drop the conditional pm_wakeup_event() call fron __device_suspend() and make the latter call pm_runtime_barrier() alone. Also modify the comment next to that call to reflect the new code and extend it to mention the need to avoid unwanted interactions between runtime PM and system-wide device suspend callbacks. Fixes: 1e2ef05bb8cf8 ("PM: Limit race conditions between runtime PM and system sleep (v2)") Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern Reported-by: Utkarsh H Patel Tested-by: Utkarsh H Patel Tested-by: Pengfei Xu Cc: All applicable Signed-off-by: Greg Kroah-Hartman

PM / core: Propagate dev->power.wakeup_path when no callbacks

2019-06-11T10:24:00+00:00

[ Upstream commit dc351d4c5f4fe4d0f274d6d660227be0c3a03317 ] The dev->power.direct_complete flag may become set in device_prepare() in case the device don't have any PM callbacks (dev->power.no_pm_callbacks is set). This leads to a broken behaviour, when there is child having wakeup enabled and relies on its parent to be used in the wakeup path. More precisely, when the direct complete path becomes selected for the child in __device_suspend(), the propagation of the dev->power.wakeup_path becomes skipped as well. Let's address this problem, by checking if the device is a part the wakeup path or has wakeup enabled, then prevent the direct complete path from being used. Reported-by: Loic Pallardy Signed-off-by: Ulf Hansson [ rjw: Comment cleanup ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

PM / core: Clear the direct_complete flag on errors

2018-10-13T07:11:32+00:00

commit 69e445ab8b66a9f30519842ef18be555d3ee9b51 upstream. If __device_suspend() runs asynchronously (in which case the device passed to it is in dpm_suspended_list at that point) and it returns early on an error or pending wakeup, and the power.direct_complete flag has been set for the device already, the subsequent device_resume() will be confused by that and it will call pm_runtime_enable() incorrectly, as runtime PM has not been disabled for the device by __device_suspend(). To avoid that, clear power.direct_complete if __device_suspend() is not going to disable runtime PM for the device before returning. Fixes: aae4518b3124 (PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily) Reported-by: Al Cooper Tested-by: Al Cooper Reviewed-by: Ulf Hansson Cc: 3.16+ # 3.16+ Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM / sleep: don't suspend parent when async child suspend_{noirq, late} fails

2016-11-26T08:54:53+00:00

commit 6f75c3fd56daf547d684127a7f83c283c3c160d1 upstream. Consider two devices, A and B, where B is a child of A, and B utilizes asynchronous suspend (it does not matter whether A is sync or async). If B fails to suspend_noirq() or suspend_late(), or is interrupted by a wakeup (pm_wakeup_pending()), then it aborts and sets the async_error variable. However, device A does not (immediately) check the async_error variable; it may continue to run its own suspend_noirq()/suspend_late() callback. This is bad. We can resolve this problem by doing our error and wakeup checking (particularly, for the async_error flag) after waiting for children to suspend, instead of before. This also helps align the logic for the noirq and late suspend cases with the logic in __device_suspend(). It's easy to observe this erroneous behavior by, for example, forcing a device to sleep a bit in its suspend_noirq() (to ensure the parent is waiting for the child to complete), then return an error, and watch the parent suspend_noirq() still get called. (Or similarly, fake a wakeup event at the right (or is it wrong?) time.) Fixes: de377b397272 (PM / sleep: Asynchronous threads for suspend_late) Fixes: 28b6fd6e3779 (PM / sleep: Asynchronous threads for suspend_noirq) Reported-by: Jeffy Chen Signed-off-by: Brian Norris Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM / sleep: Handle failures in device_suspend_late() consistently

2016-06-08T01:14:37+00:00

commit 3a17fb329da68cb00558721aff876a80bba2fdb9 upstream. Grygorii Strashko reports: The PM runtime will be left disabled for the device if its .suspend_late() callback fails and async suspend is not allowed for this device. In this case device will not be added in dpm_late_early_list and dpm_resume_early() will ignore this device, as result PM runtime will be disabled for it forever (side effect: after 8 subsequent failures for the same device the PM runtime will be reenabled due to disable_depth overflow). To fix this problem, add devices to dpm_late_early_list regardless of whether or not device_suspend_late() returns errors for them. That will ensure failures in there to be handled consistently for all devices regardless of their async suspend/resume status. Reported-by: Grygorii Strashko Tested-by: Grygorii Strashko Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM / sleep: Allow devices without runtime PM to do direct-complete

2015-07-21T21:14:22+00:00

Don't unset the direct_complete flag on devices that have runtime PM disabled, if they are runtime suspended. This is needed because otherwise ancestor devices wouldn't be able to do direct_complete without adding runtime PM support to all its descendants. Also removes pm_runtime_suspended_if_enabled() because it's now unused. Signed-off-by: Tomeu Vizoso Signed-off-by: Alan Stern Signed-off-by: Rafael J. Wysocki

Merge branch 'pm-wakeirq'

2015-06-18T23:18:14+00:00

* pm-wakeirq: PM / wakeirq: Fix typo in prototype for dev_pm_set_dedicated_wake_irq PM / Wakeirq: Add automated device wake IRQ handling

PM / sleep: trace_device_pm_callback coverage in dpm_prepare/complete

2015-06-10T00:24:49+00:00

Move the trace_device_pm_callback locations for dpm_prepare and dpm_complete to encompass the attempt to capture the device mutex prior to callback. This is needed by analyze_suspend to identify gaps in the trace output caused by the delay in locking the mutex for a device. Signed-off-by: Todd Brandt Signed-off-by: Rafael J. Wysocki

PM / Wakeirq: Add automated device wake IRQ handling

2015-05-19T23:56:31+00:00

Turns out we can automate the handling for the device_may_wakeup() quite a bit by using the kernel wakeup source list as suggested by Rafael J. Wysocki . And as some hardware has separate dedicated wake-up interrupt in addition to the IO interrupt, we can automate the handling by adding a generic threaded interrupt handler that just calls the device PM runtime to wake up the device. This allows dropping code from device drivers as we currently are doing it in multiple ways, and often wrong. For most drivers, we should be able to drop the following boilerplate code from runtime_suspend and runtime_resume functions: ... device_init_wakeup(dev, true); ... if (device_may_wakeup(dev)) enable_irq_wake(irq); ... if (device_may_wakeup(dev)) disable_irq_wake(irq); ... device_init_wakeup(dev, false); ... We can replace it with just the following init and exit time code: ... device_init_wakeup(dev, true); dev_pm_set_wake_irq(dev, irq); ... dev_pm_clear_wake_irq(dev); device_init_wakeup(dev, false); ... And for hardware with dedicated wake-up interrupts: ... device_init_wakeup(dev, true); dev_pm_set_dedicated_wake_irq(dev, irq); ... dev_pm_clear_wake_irq(dev); device_init_wakeup(dev, false); ... Signed-off-by: Tony Lindgren Signed-off-by: Rafael J. Wysocki

PM / sleep: add pm-trace support for suspending phase

2015-03-18T14:54:27+00:00

Occasionally, the system can't come back up after suspend/resume due to problems of device suspending phase. This patch make PM_TRACE infrastructure cover device suspending phase of suspend/resume process, and the information in RTC can tell developers which device suspending function make system hang. Signed-off-by: Zhonghui Fu Signed-off-by: Rafael J. Wysocki