linux-kernel - [PATCH v2 3/3] irqchip: orion: clear stale interrupts in irq

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Message-Id: <1390518632-2576-1-git-send-email-sebastian.hesselbarth@gmail.com>
Date:	Fri, 24 Jan 2014 00:10:32 +0100
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Andrew Lunn <andrew@...n.ch>,
	Gregory Clement <gregory.clement@...e-electrons.com>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] irqchip: orion: clear stale interrupts in irq_startup

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@...il.com>
---
Changelog:
v1->v2:
- use .irq_startup instead of .irq_enable (Reported by Jason Gunthorpe)

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Jason Cooper <jason@...edaemon.net>
Cc: Andrew Lunn <andrew@...n.ch>
Cc: Gregory Clement <gregory.clement@...e-electrons.com>
Cc: Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc: Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
---
 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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