If an interrupt is marked NOAUTOEN then request_irq() installs the action,
but does not enable the interrupt via startup_irq().  The interrupt is
enabled via enable_irq() later from the driver. enable_irq() calls
irq_enable().

That means that for interrupts which have a irq_startup() callback this
callback is never invoked. Neither is irq_domain_activate_irq() invoked for
such interrupts.

If an interrupt depends on irq_startup() or irq_domain_activate_irq() then
the enable via irq_enable() is not enough.

Add a status flag IRQD_IRQ_STARTED_UP and use this to select the proper
mechanism in enable_irq(). Use the flag also to avoid pointless calls into
the low level functions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/irq.h    |    6 ++++
 kernel/irq/chip.c      |   73 +++++++++++++++++++++++++++++++++++++------------
 kernel/irq/internals.h |    1 
 kernel/irq/manage.c    |    2 -
 4 files changed, 64 insertions(+), 18 deletions(-)

--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -216,6 +216,7 @@ enum {
 	IRQD_WAKEUP_ARMED		= (1 << 19),
 	IRQD_FORWARDED_TO_VCPU		= (1 << 20),
 	IRQD_AFFINITY_MANAGED		= (1 << 21),
+	IRQD_IRQ_STARTED_UP		= (1 << 22),
 };
 
 #define __irqd_to_state(d) ACCESS_PRIVATE((d)->common, state_use_accessors)
@@ -329,6 +330,11 @@ static inline void irqd_clr_activated(st
 	__irqd_to_state(d) &= ~IRQD_ACTIVATED;
 }
 
+static inline bool irqd_is_started_up(struct irq_data *d)
+{
+	return __irqd_to_state(d) & IRQD_IRQ_STARTED_UP;
+}
+
 #undef __irqd_to_state
 
 static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -185,37 +185,71 @@ static void irq_state_set_masked(struct
 	irqd_set(&desc->irq_data, IRQD_IRQ_MASKED);
 }
 
+static void irq_state_clr_started(struct irq_desc *desc)
+{
+	irqd_clear(&desc->irq_data, IRQD_IRQ_STARTED_UP);
+}
+
+static void irq_state_set_started(struct irq_desc *desc)
+{
+	irqd_set(&desc->irq_data, IRQD_IRQ_STARTED_UP);
+}
+
 int irq_startup(struct irq_desc *desc, bool resend)
 {
 	int ret = 0;
 
-	irq_state_clr_disabled(desc);
+	if (irqd_is_started_up(&desc->irq_data))
+		return 0;
+
 	desc->depth = 0;
 
 	irq_domain_activate_irq(&desc->irq_data);
 	if (desc->irq_data.chip->irq_startup) {
 		ret = desc->irq_data.chip->irq_startup(&desc->irq_data);
+		irq_state_clr_disabled(desc);
 		irq_state_clr_masked(desc);
 	} else {
 		irq_enable(desc);
 	}
+	irq_state_set_started(desc);
+
 	if (resend)
 		check_irq_resend(desc);
+
 	return ret;
 }
 
+static void __irq_disable(struct irq_desc *desc, bool mask);
+
 void irq_shutdown(struct irq_desc *desc)
 {
-	irq_state_set_disabled(desc);
-	desc->depth = 1;
-	if (desc->irq_data.chip->irq_shutdown)
-		desc->irq_data.chip->irq_shutdown(&desc->irq_data);
-	else if (desc->irq_data.chip->irq_disable)
-		desc->irq_data.chip->irq_disable(&desc->irq_data);
-	else
-		desc->irq_data.chip->irq_mask(&desc->irq_data);
+	if (irqd_is_started_up(&desc->irq_data)) {
+		desc->depth = 1;
+		if (desc->irq_data.chip->irq_shutdown) {
+			desc->irq_data.chip->irq_shutdown(&desc->irq_data);
+			irq_state_set_disabled(desc);
+			irq_state_set_masked(desc);
+		} else {
+			__irq_disable(desc, true);
+		}
+		irq_state_clr_started(desc);
+	}
+	/*
+	 * This must be called even if the interrupt was never started up,
+	 * because the activation can happen before the interrupt is
+	 * available for request/startup. It has it's own state tracking so
+	 * it's safe to call it unconditonally.
+	 */
 	irq_domain_deactivate_irq(&desc->irq_data);
-	irq_state_set_masked(desc);
+}
+
+void irq_enable_or_startup(struct irq_desc *desc)
+{
+	if (!irqd_is_started_up(&desc->irq_data))
+		irq_startup(desc, false);
+	else
+		irq_enable(desc);
 }
 
 void irq_enable(struct irq_desc *desc)
@@ -228,6 +262,17 @@ void irq_enable(struct irq_desc *desc)
 	irq_state_clr_masked(desc);
 }
 
+static void __irq_disable(struct irq_desc *desc, bool mask)
+{
+	irq_state_set_disabled(desc);
+	if (desc->irq_data.chip->irq_disable) {
+		desc->irq_data.chip->irq_disable(&desc->irq_data);
+		irq_state_set_masked(desc);
+	} else if (mask) {
+		mask_irq(desc);
+	}
+}
+
 /**
  * irq_disable - Mark interrupt disabled
  * @desc:	irq descriptor which should be disabled
@@ -250,13 +295,7 @@ void irq_enable(struct irq_desc *desc)
  */
 void irq_disable(struct irq_desc *desc)
 {
-	irq_state_set_disabled(desc);
-	if (desc->irq_data.chip->irq_disable) {
-		desc->irq_data.chip->irq_disable(&desc->irq_data);
-		irq_state_set_masked(desc);
-	} else if (irq_settings_disable_unlazy(desc)) {
-		mask_irq(desc);
-	}
+	__irq_disable(desc, irq_settings_disable_unlazy(desc));
 }
 
 void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu)
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -68,6 +68,7 @@ extern void __enable_irq(struct irq_desc
 
 extern int irq_startup(struct irq_desc *desc, bool resend);
 extern void irq_shutdown(struct irq_desc *desc);
+extern void irq_enable_or_startup(struct irq_desc *desc);
 extern void irq_enable(struct irq_desc *desc);
 extern void irq_disable(struct irq_desc *desc);
 extern void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu);
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -533,7 +533,7 @@ void __enable_irq(struct irq_desc *desc)
 			goto err_out;
 		/* Prevent probing on this irq: */
 		irq_settings_set_noprobe(desc);
-		irq_enable(desc);
+		irq_enable_or_startup(desc);
 		check_irq_resend(desc);
 		/* fall-through */
 	}