irqdomain: Allow quiet failure mode
Some interrupt controllers refuse to map interrupts marked as
"protected" by firwmare. Since we try to map everyting in the
device-tree on some platforms, we end up with a lot of nasty
WARN's in the boot log for what is a normal situation on those
machines.
This defines a specific return code (-EPERM) from the host map()
callback which cause irqdomain to fail silently.
MPIC is updated to return this when hitting a protected source
printing only a single line message for diagnostic purposes.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 96f3a1d..5a83dde 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -462,9 +462,23 @@
if (domain->ops->map) {
ret = domain->ops->map(domain, virq, hwirq);
if (ret != 0) {
- pr_err("irq-%i==>hwirq-0x%lx mapping failed: %d\n",
- virq, hwirq, ret);
- WARN_ON(1);
+ /*
+ * If map() returns -EPERM, this interrupt is protected
+ * by the firmware or some other service and shall not
+ * be mapped.
+ *
+ * Since on some platforms we blindly try to map everything
+ * we end up with a log full of backtraces.
+ *
+ * So instead, we silently fail on -EPERM, it is the
+ * responsibility of the PIC driver to display a relevant
+ * message if needed.
+ */
+ if (ret != -EPERM) {
+ pr_err("irq-%i==>hwirq-0x%lx mapping failed: %d\n",
+ virq, hwirq, ret);
+ WARN_ON(1);
+ }
irq_data->domain = NULL;
irq_data->hwirq = 0;
goto err_unmap;