Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core irq changes from Ingo Molnar:
 "The main changes:

  - generic-irqchip driver additions, cleanups and fixes

  - 3 new irqchip drivers: ARMv7-M NVIC, TB10x and Marvell Orion SoCs

  - irq_get_trigger_type() simplification and cross-arch cleanup

  - various cleanups, simplifications

  - documentation updates"

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
  softirq: Use _RET_IP_
  genirq: Add the generic chip to the genirq docbook
  genirq: generic-chip: Export some irq_gc_ functions
  genirq: Fix can_request_irq() for IRQs without an action
  irqchip: exynos-combiner: Staticize combiner_init
  irqchip: Add support for ARMv7-M NVIC
  irqchip: Add TB10x interrupt controller driver
  irqdomain: Use irq_get_trigger_type() to get IRQ flags
  MIPS: octeon: Use irq_get_trigger_type() to get IRQ flags
  arm: orion: Use irq_get_trigger_type() to get IRQ flags
  mfd: stmpe: use irq_get_trigger_type() to get IRQ flags
  mfd: twl4030-irq: Use irq_get_trigger_type() to get IRQ flags
  gpio: mvebu: Use irq_get_trigger_type() to get IRQ flags
  genirq: Add irq_get_trigger_type() to get IRQ flags
  genirq: Irqchip: document gcflags arg of irq_alloc_domain_generic_chips
  genirq: Set irq thread to RT priority on creation
  irqchip: Add support for Marvell Orion SoCs
  genirq: Add kerneldoc for irq_disable.
  genirq: irqchip: Add mask to block out invalid irqs
  genirq: Generic chip: Add linear irq domain support
  ...

1 files changed, 13 insertions, 0 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index cbd97ce0b00..a3bb14fbe5c 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -213,6 +213,19 @@ void irq_enable(struct irq_desc *desc)
 	irq_state_clr_masked(desc);
 }
 
+/**
+ * irq_disable - Mark interupt disabled
+ * @desc:	irq descriptor which should be disabled
+ *
+ * If the chip does not implement the irq_disable callback, we
+ * use a lazy disable approach. That means we mark the interrupt
+ * disabled, but leave the hardware unmasked. That's an
+ * optimization because we avoid the hardware access for the
+ * common case where no interrupt happens after we marked it
+ * disabled. If an interrupt happens, then the interrupt flow
+ * handler masks the line at the hardware level and marks it
+ * pending.
+ */
 void irq_disable(struct irq_desc *desc)
 {
 	irq_state_set_disabled(desc);