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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-02-27 00:07:55 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-03-04 21:42:19 +0100
commit17f480342026e54000731acaa69bf32787ce46cb (patch)
tree69e420a6043d73c3395aa7bde14d6347892d4af2 /kernel
parentgenirq / PM: better describe IRQF_NO_SUSPEND semantics (diff)
downloadlinux-dev-17f480342026e54000731acaa69bf32787ce46cb.tar.xz
linux-dev-17f480342026e54000731acaa69bf32787ce46cb.zip
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 9ce7a25849e8 (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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/irq/manage.c7
-rw-r--r--kernel/irq/pm.c7
2 files changed, 12 insertions, 2 deletions
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 196a06fbc122..886d09e691d5 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1474,8 +1474,13 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
* otherwise we'll have trouble later trying to figure out
* which interrupt is which (messes up the interrupt freeing
* logic etc).
+ *
+ * Also IRQF_COND_SUSPEND only makes sense for shared interrupts and
+ * it cannot be set along with IRQF_NO_SUSPEND.
*/
- if ((irqflags & IRQF_SHARED) && !dev_id)
+ if (((irqflags & IRQF_SHARED) && !dev_id) ||
+ (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) ||
+ ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND)))
return -EINVAL;
desc = irq_to_desc(irq);
diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
index 3ca532592704..5204a6d1b985 100644
--- a/kernel/irq/pm.c
+++ b/kernel/irq/pm.c
@@ -43,9 +43,12 @@ void irq_pm_install_action(struct irq_desc *desc, struct irqaction *action)
if (action->flags & IRQF_NO_SUSPEND)
desc->no_suspend_depth++;
+ else if (action->flags & IRQF_COND_SUSPEND)
+ desc->cond_suspend_depth++;
WARN_ON_ONCE(desc->no_suspend_depth &&
- desc->no_suspend_depth != desc->nr_actions);
+ (desc->no_suspend_depth +
+ desc->cond_suspend_depth) != desc->nr_actions);
}
/*
@@ -61,6 +64,8 @@ void irq_pm_remove_action(struct irq_desc *desc, struct irqaction *action)
if (action->flags & IRQF_NO_SUSPEND)
desc->no_suspend_depth--;
+ else if (action->flags & IRQF_COND_SUSPEND)
+ desc->cond_suspend_depth--;
}
static bool suspend_device_irq(struct irq_desc *desc, int irq)