linux/kernel/irq
Rafael J. Wysocki 17f4803420 genirq / PM: Add flag for shared NO_SUSPEND interrupt lines
It currently is required that all users of NO_SUSPEND interrupt
lines pass the IRQF_NO_SUSPEND flag when requesting the IRQ or the
WARN_ON_ONCE() in irq_pm_install_action() will trigger.  That is
done to warn about situations in which unprepared interrupt handlers
may be run unnecessarily for suspended devices and may attempt to
access those devices by mistake.  However, it may cause drivers
that have no technical reasons for using IRQF_NO_SUSPEND to set
that flag just because they happen to share the interrupt line
with something like a timer.

Moreover, the generic handling of wakeup interrupts introduced by
commit 9ce7a25849 (genirq: Simplify wakeup mechanism) only works
for IRQs without any NO_SUSPEND users, so the drivers of wakeup
devices needing to use shared NO_SUSPEND interrupt lines for
signaling system wakeup generally have to detect wakeup in their
interrupt handlers.  Thus if they happen to share an interrupt line
with a NO_SUSPEND user, they also need to request that their
interrupt handlers be run after suspend_device_irqs().

In both cases the reason for using IRQF_NO_SUSPEND is not because
the driver in question has a genuine need to run its interrupt
handler after suspend_device_irqs(), but because it happens to
share the line with some other NO_SUSPEND user.  Otherwise, the
driver would do without IRQF_NO_SUSPEND just fine.

To make it possible to specify that condition explicitly, introduce
a new IRQ action handler flag for shared IRQs, IRQF_COND_SUSPEND,
that, when set, will indicate to the IRQ core that the interrupt
user is generally fine with suspending the IRQ, but it also can
tolerate handler invocations after suspend_device_irqs() and, in
particular, it is capable of detecting system wakeup and triggering
it as appropriate from its interrupt handler.

That will allow us to work around a problem with a shared timer
interrupt line on at91 platforms.

Link: http://marc.info/?l=linux-kernel&m=142252777602084&w=2
Link: http://marc.info/?t=142252775300011&r=1&w=2
Link: https://lkml.org/lkml/2014/12/15/552
Reported-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
2015-03-04 21:42:19 +01:00
..
Kconfig genirq: Add generic msi irq domain support 2014-11-23 13:01:47 +01:00
Makefile genirq: Add generic msi irq domain support 2014-11-23 13:01:47 +01:00
autoprobe.c genirq: Handle pending irqs in irq_startup() 2012-02-15 11:56:59 +01:00
chip.c genirq: Work around __irq_set_handler vs stacked domains ordering issues 2014-11-23 13:01:47 +01:00
debug.h irq: hide debug macros so they don't collide with others. 2012-04-23 12:30:03 -04:00
devres.c genirq: fix reference in devm_request_threaded_irq comment 2014-08-28 15:22:00 +02:00
dummychip.c genirq: Export dummy_irq_chip 2012-08-21 16:14:23 +02:00
generic-chip.c genirq: Generic chip: Add big endian I/O accessors 2014-11-09 04:02:00 +00:00
handle.c genirq: Export symbol no_action() 2014-03-22 11:33:09 +01:00
internals.h genirq: Prevent proc race against freeing of irq descriptors 2014-12-13 13:33:07 +01:00
irqdesc.c genirq: Prevent proc race against freeing of irq descriptors 2014-12-13 13:33:07 +01:00
irqdomain.c irqdomain: Introduce helper function irq_domain_add_hierarchy() 2014-11-23 13:01:46 +01:00
manage.c genirq / PM: Add flag for shared NO_SUSPEND interrupt lines 2015-03-04 21:42:19 +01:00
migration.c genirq: Introduce irq_do_set_affinity() to reduce duplicated code 2012-05-24 22:36:40 +02:00
msi.c genirq: Move irq_chip_write_msi_msg() helper to core 2014-12-07 21:49:45 +01:00
pm.c genirq / PM: Add flag for shared NO_SUSPEND interrupt lines 2015-03-04 21:42:19 +01:00
proc.c irq: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:38 -08:00
resend.c genirq: Provide means to retrigger parent 2012-11-01 12:11:31 +01:00
settings.h genirq: Prevent spurious detection for unconditionally polled interrupts 2013-11-13 16:03:02 +01:00
spurious.c genirq: Sanitize spurious interrupt detection of threaded irqs 2014-05-03 23:15:39 +02:00