MIPS: ralink: add missing comment in irq driver

Trivial patch that adds a comment that makes the code more readable.

Signed-off-by: John Crispin <blogic@openwrt.org>
Acked-by: Gabor Juhos <juhosg@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/5168/

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/mips/ralink/irq.c b/arch/mips/ralink/irq.c
index d9807d0587cd..320b1f1043ff 100644
--- a/arch/mips/ralink/irq.c
+++ b/arch/mips/ralink/irq.c
@@ -166,6 +166,7 @@ static int __init intc_of_init(struct device_node *node,
         irq_set_chained_handler(irq, ralink_intc_irq_handler);
         irq_set_handler_data(irq, domain);
 
+        /* tell the kernel which irq is used for performance monitoring */
         cp0_perfcount_irq = irq_create_mapping(domain, 9);
 
         return 0;