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Subject[PATCH] irq: Add new flag to ack level-triggered interrupts before unmasking
Date
Several irqchip drivers require the level-triggered interrupt to be
acked before unmasking to avoid that a second interrupt is immediately
triggered. This small patch introduces a new irqchip flags that is used
to ack the IRQ line before it is unmasked.

Signed-off-by: Carlo Caione <carlo@caione.org>
---
include/linux/irq.h | 2 ++
kernel/irq/chip.c | 10 ++++++++++
kernel/irq/internals.h | 1 +
kernel/irq/manage.c | 2 +-
4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 7dc1003..2cbe8d1 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -349,6 +349,7 @@ struct irq_chip {
* IRQCHIP_ONOFFLINE_ENABLED: Only call irq_on/off_line callbacks
* when irq enabled
* IRQCHIP_SKIP_SET_WAKE: Skip chip.irq_set_wake(), for this irq chip
+ * IRQCHIP_ACK_ON_UNMASK: Ack level interrupts right before unmask
*/
enum {
IRQCHIP_SET_TYPE_MASKED = (1 << 0),
@@ -357,6 +358,7 @@ enum {
IRQCHIP_ONOFFLINE_ENABLED = (1 << 3),
IRQCHIP_SKIP_SET_WAKE = (1 << 4),
IRQCHIP_ONESHOT_SAFE = (1 << 5),
+ IRQCHIP_ACK_ON_UNMASK = (1 << 6),
};

/* This include will go away once we isolated irq_desc usage to core code */
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index dc04c16..9d2d2e2 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -265,6 +265,16 @@ static inline void mask_ack_irq(struct irq_desc *desc)
irq_state_set_masked(desc);
}

+void ack_unmask_irq(struct irq_desc *desc)
+{
+ if ((desc->irq_data.chip->flags & IRQCHIP_ACK_ON_UNMASK) &&
+ (irqd_get_trigger_type(&desc->irq_data) & IRQ_TYPE_LEVEL_MASK) &&
+ desc->irq_data.chip->irq_ack)
+ desc->irq_data.chip->irq_ack(&desc->irq_data);
+
+ unmask_irq(desc);
+}
+
void mask_irq(struct irq_desc *desc)
{
if (desc->irq_data.chip->irq_mask) {
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 001fa5b..06ff850 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -73,6 +73,7 @@ extern void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu);
extern void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu);
extern void mask_irq(struct irq_desc *desc);
extern void unmask_irq(struct irq_desc *desc);
+extern void ack_unmask_irq(struct irq_desc *desc);

extern void init_kstat_irqs(struct irq_desc *desc, int node, int nr);

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 481a13c..39505d8 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -718,7 +718,7 @@ again:

if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
irqd_irq_masked(&desc->irq_data))
- unmask_irq(desc);
+ ack_unmask_irq(desc);

out_unlock:
raw_spin_unlock_irq(&desc->lock);
--
1.8.5.3


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