genirq: Handle pending irqs in irq_startup()

BugLink: http://bugs.launchpad.net/bugs/954576

commit b4bc724e82e80478cba5fe9825b62e71ddf78757 upstream.

An interrupt might be pending when irq_startup() is called, but the
startup code does not invoke the resend logic. In some cases this
prevents the device from issuing another interrupt which renders the
device non functional.

Call the resend function in irq_startup() to keep things going.

Reported-and-tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 3322a34d9ee..ca14f5dcabd 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -157,19 +157,22 @@ static void irq_state_set_masked(struct irq_desc *desc)
         irqd_set(&desc->irq_data, IRQD_IRQ_MASKED);
 }
 
-int irq_startup(struct irq_desc *desc)
+int irq_startup(struct irq_desc *desc, bool resend)
 {
+        int ret = 0;
+
         irq_state_clr_disabled(desc);
         desc->depth = 0;
 
         if (desc->irq_data.chip->irq_startup) {
-                int ret = desc->irq_data.chip->irq_startup(&desc->irq_data);
+                ret = desc->irq_data.chip->irq_startup(&desc->irq_data);
                 irq_state_clr_masked(desc);
-                return ret;
+        } else {
+                irq_enable(desc);
         }
-
-        irq_enable(desc);
-        return 0;
+        if (resend)
+                check_irq_resend(desc, desc->irq_data.irq);
+        return ret;
 }
 
 void irq_shutdown(struct irq_desc *desc)
@@ -596,7 +599,7 @@ __irq_set_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
                 irq_settings_set_noprobe(desc);
                 irq_settings_set_norequest(desc);
                 irq_settings_set_nothread(desc);
-                irq_startup(desc);
+                irq_startup(desc, true);
         }
 out:
         irq_put_desc_busunlock(desc, flags);