[PATCH v1] mtd: parsers: ofpart: Fix parsing when size-cells is 0

[Francesco Dolcini <francesco@dolcini.it>]

From: Francesco Dolcini <francesco.dolcini@toradex.com>

Add a fallback mechanism to handle the case in which #size-cells is set
to <0>. According to the DT binding the nand controller node should have
set it to 0 and this is not compatible with the legacy way of
specifying partitions directly as child nodes of the nand-controller node.

This fixes a boot failure on colibri-imx7 and potentially other boards.

Cc: stable@vger.kernel.org
Fixes: 753395ea1e45 ("ARM: dts: imx7: Fix NAND controller size-cells")
Link: https://lore.kernel.org/all/Y4dgBTGNWpM6SQXI@francesco-nb.int.toradex.com/
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
---
 drivers/mtd/parsers/ofpart_core.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/mtd/parsers/ofpart_core.c b/drivers/mtd/parsers/ofpart_core.c
index 192190c42fc8..aa3b7fa61e50 100644
--- a/drivers/mtd/parsers/ofpart_core.c
+++ b/drivers/mtd/parsers/ofpart_core.c
@@ -122,6 +122,17 @@ static int parse_fixed_partitions(struct mtd_info *master,
 
 		a_cells = of_n_addr_cells(pp);
 		s_cells = of_n_size_cells(pp);
+		if (s_cells == 0) {
+			/*
+			 * Use #size-cells = <1> for backward compatibility
+			 * in case #size-cells is set to <0> and firmware adds
+			 * OF partitions without setting it.
+			 */
+			pr_warn_once("%s: ofpart partition %pOF (%pOF) #size-cells is <0>, using <1> for backward compatibility.\n",
+				     master->name, pp,
+				     mtd_node);
+			s_cells = 1;
+		}
 		if (len / 4 != a_cells + s_cells) {
 			pr_debug("%s: ofpart partition %pOF (%pOF) error parsing reg property.\n",
 				 master->name, pp,
-- 
2.25.1