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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-03-06 01:29:05 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-03-06 01:29:05 +0100 |
| commit | 79d223646baa14272dc90044a0e798c552b72eda (patch) | |
| tree | a4f92bc30b14595242d1b60705b93e3f86afc59f /Documentation | |
| parent | Merge branch 'suspend-to-idle' (diff) | |
| parent | genirq / PM: describe IRQF_COND_SUSPEND (diff) | |
| download | linux-79d223646baa14272dc90044a0e798c552b72eda.tar.xz linux-79d223646baa14272dc90044a0e798c552b72eda.zip | |
Merge branch 'irq-pm'
* irq-pm:
genirq / PM: describe IRQF_COND_SUSPEND
tty: serial: atmel: rework interrupt and wakeup handling
watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND
clk: at91: implement suspend/resume for the PMC irqchip
rtc: at91rm9200: rework wakeup and interrupt handling
rtc: at91sam9: rework wakeup and interrupt handling
PM / wakeup: export pm_system_wakeup symbol
genirq / PM: Add flag for shared NO_SUSPEND interrupt lines
genirq / PM: better describe IRQF_NO_SUSPEND semantics
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/power/suspend-and-interrupts.txt | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/Documentation/power/suspend-and-interrupts.txt b/Documentation/power/suspend-and-interrupts.txt index 2f9c5a5fcb25..8afb29a8604a 100644 --- a/Documentation/power/suspend-and-interrupts.txt +++ b/Documentation/power/suspend-and-interrupts.txt @@ -40,8 +40,10 @@ but also to IPIs and to some other special-purpose interrupts. The IRQF_NO_SUSPEND flag is used to indicate that to the IRQ subsystem when requesting a special-purpose interrupt. It causes suspend_device_irqs() to -leave the corresponding IRQ enabled so as to allow the interrupt to work all -the time as expected. +leave the corresponding IRQ enabled so as to allow the interrupt to work as +expected during the suspend-resume cycle, but does not guarantee that the +interrupt will wake the system from a suspended state -- for such cases it is +necessary to use enable_irq_wake(). Note that the IRQF_NO_SUSPEND flag affects the entire IRQ and not just one user of it. Thus, if the IRQ is shared, all of the interrupt handlers installed @@ -110,8 +112,9 @@ any special interrupt handling logic for it to work. IRQF_NO_SUSPEND and enable_irq_wake() ------------------------------------- -There are no valid reasons to use both enable_irq_wake() and the IRQF_NO_SUSPEND -flag on the same IRQ. +There are very few valid reasons to use both enable_irq_wake() and the +IRQF_NO_SUSPEND flag on the same IRQ, and it is never valid to use both for the +same device. First of all, if the IRQ is not shared, the rules for handling IRQF_NO_SUSPEND interrupts (interrupt handlers are invoked after suspend_device_irqs()) are @@ -120,4 +123,13 @@ handlers are not invoked after suspend_device_irqs()). Second, both enable_irq_wake() and IRQF_NO_SUSPEND apply to entire IRQs and not to individual interrupt handlers, so sharing an IRQ between a system wakeup -interrupt source and an IRQF_NO_SUSPEND interrupt source does not make sense. +interrupt source and an IRQF_NO_SUSPEND interrupt source does not generally +make sense. + +In rare cases an IRQ can be shared between a wakeup device driver and an +IRQF_NO_SUSPEND user. In order for this to be safe, the wakeup device driver +must be able to discern spurious IRQs from genuine wakeup events (signalling +the latter to the core with pm_system_wakeup()), must use enable_irq_wake() to +ensure that the IRQ will function as a wakeup source, and must request the IRQ +with IRQF_COND_SUSPEND to tell the core that it meets these requirements. If +these requirements are not met, it is not valid to use IRQF_COND_SUSPEND. |