of/address: Translate 'dma-ranges' for parent nodes missing 'dma-ranges'

'dma-ranges' frequently exists without parent nodes having 'dma-ranges'.
While this is an error for 'ranges', this is fine because DMA capable
devices always have a translatable DMA address. Also, with no
'dma-ranges' at all, the assumption is that DMA addresses are 1:1 with
no restrictions unless perhaps the device itself has implicit
restrictions.

Cc: Robin Murphy <robin.murphy@arm.com>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 887c0413f64826a51d49770b1efd866583e7c66c..1c291bd6bce20e0835975124964fa7d76438288a 100644 (file)
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -519,9 +519,13 @@ static int of_translate_one(struct device_node *parent, struct of_bus *bus,
         *
         * As far as we know, this damage only exists on Apple machines, so
         * This code is only enabled on powerpc. --gcl
+        *
+        * This quirk also applies for 'dma-ranges' which frequently exist in
+        * child nodes without 'dma-ranges' in the parent nodes. --RobH
         */
        ranges = of_get_property(parent, rprop, &rlen);
-       if (ranges == NULL && !of_empty_ranges_quirk(parent)) {
+       if (ranges == NULL && !of_empty_ranges_quirk(parent) &&
+           strcmp(rprop, "dma-ranges")) {
                pr_debug("no ranges; cannot translate\n");
                return 1;
        }