[PATCH 3.11 005/131] irqchip: orion: clear stale interrupts in irq_startup

[Luis Henriques]

3.11.10.6 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sebastian Hesselbarth <sebastian.hesselbarth at gmail.com>

commit e0318ec3bf3f1502cd11b21b1eb00aa355b40b67 upstream.

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 at gmail.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia at free-electrons.com>
Signed-off-by: Jason Cooper <jason at lakedaemon.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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 1f636f7..0dfdc5c 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;
-- 
1.9.0