Consider two devices A and B sharing an irq and B already asserts the irq on
a booting machine.
If the driver for A is loaded first the irq starts triggering and gets
disabled after some time by note_interrupt(). Later when the driver for B
is loaded the interrupt should be reenabled---other wise both A and B don't
work properly.
Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
kernel/irq/manage.c | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 438a014..831ebb2 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -365,11 +365,18 @@ int setup_irq(unsigned int irq, struct irqaction *new)
desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
IRQ_INPROGRESS);
+ }
+
+ /* in the shared case the interrupt might be disabled if a device
+ * asserts the irq but the corresponding driver wasn't the first to be
+ * loaded. So retry enabling the irq.
+ */
+ if (!shared || desc->status & IRQ_DISABLED) {
if (!(desc->status & IRQ_NOAUTOEN)) {
desc->depth = 0;
desc->status &= ~IRQ_DISABLED;
- if (desc->chip->startup)
+ if (!shared && desc->chip->startup)
desc->chip->startup(irq);
else
desc->chip->enable(irq);
--
1.5.5.1
--
