doc: dt: mtd: partitions: add compatible property to "partitions" node

computersforpeace · computersforpeace · commit e488ca9f8d4f · 2015-12-08T17:10:20.000-08:00
As noted here [1], there are potentially future conflicts if we try to use MTD's "partitions" subnode to describe anything besides just the fixed-in-the-device-tree partitions currently described in this document. Particularly, there was a proposal to use this node for the AFS parser too. It can pose a (small) problem to try to differentiate the following nodes: // using binding as currently specified partitions { #address-cells = <x>; #size-cells = <y>; partition@0 { ...; }; }; and // proposed future binding partitions { compatible = "arm,arm-flash-structure"; }; It's especially difficult if other uses of this node start having subnodes. So, since the "partitions" node is new in v4.4, let's fixup the binding before release so that it requires a compatible property, so it's much clearer to distinguish. e.g.: // proposed partitions { compatible = "fixed-partitions"; #address-cells = <x>; #size-cells = <y>; partition@0 { ...; }; }; [1] Subject: "mtd: create a partition type device tree binding" http://lkml.kernel.org/g/20151113220039.GA74382@google.com http://lists.infradead.org/pipermail/linux-mtd/2015-November/063355.html http://lists.infradead.org/pipermail/linux-mtd/2015-November/063364.html Cc: Michal Suchanek <hramrach@gmail.com> Signed-off-by: Brian Norris <computersforpeace@gmail.com> Acked-by: Rob Herring <robh@kernel.org>
diff --git a/Documentation/devicetree/bindings/mtd/partition.txt b/Documentation/devicetree/bindings/mtd/partition.txt
@@ -6,7 +6,9 @@ used for what purposes, but which don't use an on-flash partition table such
 as RedBoot.
 
 The partition table should be a subnode of the mtd node and should be named
-'partitions'. Partitions are defined in subnodes of the partitions node.
+'partitions'. This node should have the following property:
+- compatible : (required) must be "fixed-partitions"
+Partitions are then defined in subnodes of the partitions node.
 
 For backwards compatibility partitions as direct subnodes of the mtd device are
 supported. This use is discouraged.
@@ -36,6 +38,7 @@ Examples:
 
 flash@0 {
 	partitions {
+		compatible = "fixed-partitions";
 		#address-cells = <1>;
 		#size-cells = <1>;
 
@@ -53,6 +56,7 @@ flash@0 {
 
 flash@1 {
 	partitions {
+		compatible = "fixed-partitions";
 		#address-cells = <1>;
 		#size-cells = <2>;
 
@@ -66,6 +70,7 @@ flash@1 {
 
 flash@2 {
 	partitions {
+		compatible = "fixed-partitions";
 		#address-cells = <2>;
 		#size-cells = <2>;
 
diff --git a/drivers/mtd/ofpart.c b/drivers/mtd/ofpart.c
@@ -55,6 +55,9 @@ static int parse_ofpart_partitions(struct mtd_info *master,
 			 master->name, mtd_node->full_name);
 		ofpart_node = mtd_node;
 		dedicated = false;
+	} else if (!of_device_is_compatible(ofpart_node, "fixed-partitions")) {
+		/* The 'partitions' subnode might be used by another parser */
+		return 0;
 	}
 
 	/* First count the subnodes */

Original file line number	Diff line number	Diff line change
`@@ -55,6 +55,9 @@ static int parse_ofpart_partitions(struct mtd_info *master,`
`55`	`55`	`master->name, mtd_node->full_name);`
`56`	`56`	`ofpart_node = mtd_node;`
`57`	`57`	`dedicated = false;`
	`58`	`+ } else if (!of_device_is_compatible(ofpart_node, "fixed-partitions")) {`
	`59`	`+ /* The 'partitions' subnode might be used by another parser */`
	`60`	`+ return 0;`
`58`	`61`	`}`
`59`	`62`
`60`	`63`	`/* First count the subnodes */`