[tip:irq/urgent] genirq: Don' t return ENOSYS in irq_chip_retrigger_hierarchy

[tip-bot for Grygorii Strashko <tipbot@zytor.com>]

Commit-ID:  6d4affea7d5aa5ca5ff4c3e5fbf3ee16801cc527
Gitweb:     http://git.kernel.org/tip/6d4affea7d5aa5ca5ff4c3e5fbf3ee16801cc527
Author:     Grygorii Strashko <grygorii.strashko@ti.com>
AuthorDate: Fri, 14 Aug 2015 15:20:25 +0300
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 20 Aug 2015 00:25:25 +0200

genirq: Don't return ENOSYS in irq_chip_retrigger_hierarchy

irq_chip_retrigger_hierarchy() returns -ENOSYS if it was not able to
find at least one .irq_retrigger() callback implemented in the IRQ
domain hierarchy.

That's wrong, because check_irq_resend() expects a 0 return value from
the callback in case that the hardware assisted resend was not
possible. If the return value is non zero the core code assumes
hardware resend success and the software resend is not invoked.

This results in lost interrupts on platforms where none of the parent
irq chips in the hierarchy implements the retrigger callback.

This is observable on TI OMAP, where the hierarchy is:

 ARM GIC <- OMAP wakeupgen <- TI Crossbar

Return 0 instead so the software resend mechanism gets invoked.

[ tglx: Massaged changelog ]

Fixes: 85f08c17de26 ('genirq: Introduce helper functions...')
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: <linux@arm.linux.org.uk>
Cc: <nsekhar@ti.com>
Cc: <jason@lakedaemon.net>
Cc: <balbi@ti.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: <tony@atomide.com>
Cc: stable@vger.kernel.org # 4.1
Link: http://lkml.kernel.org/r/1439554830-19502-2-git-send-email-grygorii.strashko@ti.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/irq/chip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 27f4332..6de638b 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -997,7 +997,7 @@ int irq_chip_retrigger_hierarchy(struct irq_data *data)
 		if (data->chip && data->chip->irq_retrigger)
 			return data->chip->irq_retrigger(data);
 
-	return -ENOSYS;
+	return 0;
 }
 
 /**