of/irq: Fix lookup to use 'interrupts-extended' property first

In case the Device Tree blob passed by the boot agent supplies both an
'interrupts-extended' and an 'interrupts' property in order to allow for
older kernels to be usable, prefer the new-style 'interrupts-extended'
property which conveys a lot more information.

This allows us to have bootloaders willingly maintaining backwards
compatibility with older kernels without entirely deprecating the
'interrupts' property.

Update the bindings documentation to describe a situation where both the
'interrupts-extended' and the 'interrupts' property are present, and
which one takes precedence over the other.

Cc: stable@vger.kernel.org # 3.13+
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 3e06a699352d..1471e0a223a5 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -301,16 +301,17 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
         /* Get the reg property (if any) */
         addr = of_get_property(device, "reg", NULL);
 
+        /* Try the new-style interrupts-extended first */
+        res = of_parse_phandle_with_args(device, "interrupts-extended",
+                                        "#interrupt-cells", index, out_irq);
+        if (!res)
+                return of_irq_parse_raw(addr, out_irq);
+
         /* Get the interrupts property */
         intspec = of_get_property(device, "interrupts", &intlen);
-        if (intspec == NULL) {
-                /* Try the new-style interrupts-extended */
-                res = of_parse_phandle_with_args(device, "interrupts-extended",
-                                                "#interrupt-cells", index, out_irq);
-                if (res)
-                        return -EINVAL;
-                return of_irq_parse_raw(addr, out_irq);
-        }
+        if (intspec == NULL)
+                return -EINVAL;
+
         intlen /= sizeof(*intspec);
 
         pr_debug(" intspec=%d intlen=%d\n", be32_to_cpup(intspec), intlen);