genirq: Handle NOAUTOEN interrupt setup proper

If an interrupt is marked NOAUTOEN then request_irq() installs the action,
but does not enable the interrupt via startup_irq().  The interrupt is
enabled via enable_irq() later from the driver. enable_irq() calls
irq_enable().

That means that for interrupts which have a irq_startup() callback this
callback is never invoked. Neither is irq_domain_activate_irq() invoked for
such interrupts.

If an interrupt depends on irq_startup() or irq_domain_activate_irq() then
the enable via irq_enable() is not enough.

Add a status flag IRQD_IRQ_STARTED_UP and use this to select the proper
mechanism in enable_irq(). Use the flag also to avoid pointless calls into
the low level functions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: dianders@chromium.org
Cc: jeffy <jeffy.chen@rock-chips.com>
Cc: Brian Norris <briannorris@chromium.org>
Cc: tfiga@chromium.org
Link: http://lkml.kernel.org/r/20170531100212.130986205@linutronix.de

1 files changed, 9 insertions, 3 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 070be98..5705610 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -533,9 +533,15 @@ void __enable_irq(struct irq_desc *desc)
 			goto err_out;
 		/* Prevent probing on this irq: */
 		irq_settings_set_noprobe(desc);
-		irq_enable(desc);
-		check_irq_resend(desc);
-		/* fall-through */
+		/*
+		 * Call irq_startup() not irq_enable() here because the
+		 * interrupt might be marked NOAUTOEN. So irq_startup()
+		 * needs to be invoked when it gets enabled the first
+		 * time. If it was already started up, then irq_startup()
+		 * will invoke irq_enable() under the hood.
+		 */
+		irq_startup(desc, true);
+		break;
 	}
 	default:
 		desc->depth--;