[PATCH v2 3/3] irqchip: orion: clear stale interrupts in irq_startup

From: Sebastian Hesselbarth
Date: Thu Jan 23 2014 - 18:10:57 EST


Bridge IRQ_CAUSE bits are asserted regardless of the corresponding bit in
IRQ_MASK register. To avoid interrupt events on stale irqs, we have to clear
them before unmask. This installs an .irq_startup callback to ensure stale
irqs are cleared before initial unmask.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
---
Changelog:
v1->v2:
- use .irq_startup instead of .irq_enable (Reported by Jason Gunthorpe)

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Jason Cooper <jason@xxxxxxxxxxxxxx>
Cc: Andrew Lunn <andrew@xxxxxxx>
Cc: Gregory Clement <gregory.clement@xxxxxxxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgunthorpe@xxxxxxxxxxxxxxxxxxxx>
Cc: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
drivers/irqchip/irq-orion.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/irqchip/irq-orion.c b/drivers/irqchip/irq-orion.c
index 1f636f719065..0dfdc5c824a1 100644
--- a/drivers/irqchip/irq-orion.c
+++ b/drivers/irqchip/irq-orion.c
@@ -123,6 +123,19 @@ static void orion_bridge_irq_handler(unsigned int irq, struct irq_desc *desc)
}
}

+/*
+ * Bridge IRQ_CAUSE is asserted regardless of IRQ_MASK register.
+ * To avoid interrupt events on stale irqs, we clear them before unmask.
+ */
+static unsigned int orion_bridge_irq_startup(struct irq_data *d)
+{
+ struct irq_chip_type *ct = irq_data_get_chip_type(d);
+
+ ct->chip.irq_ack(d);
+ ct->chip.irq_unmask(d);
+ return 0;
+}
+
static int __init orion_bridge_irq_init(struct device_node *np,
struct device_node *parent)
{
@@ -176,6 +189,7 @@ static int __init orion_bridge_irq_init(struct device_node *np,

gc->chip_types[0].regs.ack = ORION_BRIDGE_IRQ_CAUSE;
gc->chip_types[0].regs.mask = ORION_BRIDGE_IRQ_MASK;
+ gc->chip_types[0].chip.irq_startup = orion_bridge_irq_startup;
gc->chip_types[0].chip.irq_ack = irq_gc_ack_clr_bit;
gc->chip_types[0].chip.irq_mask = irq_gc_mask_clr_bit;
gc->chip_types[0].chip.irq_unmask = irq_gc_mask_set_bit;
--
1.8.5.2

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