[PATCH 4.1 68/78] genirq: Dont return ENOSYS in irq_chip_retrigger_hierarchy

[Greg Kroah-Hartman]

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

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

From: Grygorii Strashko <grygorii.strashko at ti.com>

commit 6d4affea7d5aa5ca5ff4c3e5fbf3ee16801cc527 upstream.

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 at ti.com>
Reviewed-by: Marc Zyngier <marc.zyngier at arm.com>
Reviewed-by: Jiang Liu <jiang.liu at linux.intel.com>
Cc: Sudeep Holla <sudeep.holla at arm.com>
Cc: <linux at arm.linux.org.uk>
Cc: <nsekhar at ti.com>
Cc: <jason at lakedaemon.net>
Cc: <balbi at ti.com>
Cc: <linux-arm-kernel at lists.infradead.org>
Cc: <tony at atomide.com>
Link: http://lkml.kernel.org/r/1439554830-19502-2-git-send-email-grygorii.strashko@ti.com
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>

---
 kernel/irq/chip.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -946,7 +946,7 @@ int irq_chip_retrigger_hierarchy(struct
 		if (data->chip && data->chip->irq_retrigger)
 			return data->chip->irq_retrigger(data);
 
-	return -ENOSYS;
+	return 0;
 }
 
 /**