mtd: parsers: ofpart: fix parsing subpartitions

ofpart was recently patched to not scan random partition nodes as
subpartitions. That change unfortunately broke scanning valid
subpartitions like:

partitions {
	compatible = "fixed-partitions";
	#address-cells = <1>;
	#size-cells = <1>;

	partition@0 {
		compatible = "fixed-partitions";
		label = "bootloader";
		reg = <0x0 0x100000>;

		partition@0 {
			label = "config";
			reg = <0x80000 0x80000>;
		};
	};
};

Fix that regression by adding 1 more code path. We actually need 3
conditional blocks to support 3 possible cases. This change also makes
code easier to understand & follow.

Reported-by: David Bauer <mail@david-bauer.net>
Fixes: 2d751203aacf ("mtd: parsers: ofpart: limit parsing of deprecated DT syntax
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Tested-by: Andrew Cameron <apcameron@softhome.net>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210508173214.28365-1-zajec5@gmail.com

diff --git a/drivers/mtd/parsers/ofpart_core.c b/drivers/mtd/parsers/ofpart_core.c
index 0fd8d2a..192190c 100644 (file)
--- a/drivers/mtd/parsers/ofpart_core.c
+++ b/drivers/mtd/parsers/ofpart_core.c
@@ -57,20 +57,22 @@ static int parse_fixed_partitions(struct mtd_info *master,
        if (!mtd_node)
                return 0;
 
-       ofpart_node = of_get_child_by_name(mtd_node, "partitions");
-       if (!ofpart_node && !master->parent) {
-               /*
-                * We might get here even when ofpart isn't used at all (e.g.,
-                * when using another parser), so don't be louder than
-                * KERN_DEBUG
-                */
-               pr_debug("%s: 'partitions' subnode not found on %pOF. Trying to parse direct subnodes as partitions.\n",
-                        master->name, mtd_node);
+       if (!master->parent) { /* Master */
+               ofpart_node = of_get_child_by_name(mtd_node, "partitions");
+               if (!ofpart_node) {
+                       /*
+                        * We might get here even when ofpart isn't used at all (e.g.,
+                        * when using another parser), so don't be louder than
+                        * KERN_DEBUG
+                        */
+                       pr_debug("%s: 'partitions' subnode not found on %pOF. Trying to parse direct subnodes as partitions.\n",
+                               master->name, mtd_node);
+                       ofpart_node = mtd_node;
+                       dedicated = false;
+               }
+       } else { /* Partition */
                ofpart_node = mtd_node;
-               dedicated = false;
        }
-       if (!ofpart_node)
-               return 0;
 
        of_id = of_match_node(parse_ofpart_match_table, ofpart_node);
        if (dedicated && !of_id) {