[PATCH master] of: overlay: don't do fixups on empty global.of.overlay.dir

[Ahmad Fatoum]

$global.of.overlay.dir is dynamically prepended with the root of the
device currently being booted. This allows use of relative paths.

Because $global.of.overlay.filepattern is * by default, this means that
all files in the root of the device will be considered overlays and
barebox will try to unflatten them leading to an error message on boot:

  ERROR: of_overlay: Failed to unflatten /mnt/mmc0.4//.root_is_rw:
	Invalid argument

Fix this by not doing any fixups at all on empty global.of.overlay.dir.

If for whatever reason, a user wants overlays at /, they can

  global.of.overlay.dir=.

Fixes: 124c64af0982 ("overlay: Add filters to choose which overlays to apply")
Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 drivers/of/overlay.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 42b309805fd2..25140eed31ed 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -460,6 +460,9 @@ static int of_overlay_global_fixup(struct device_node *root, void *data)
 	if (*of_overlay_dir == '/')
 		return of_overlay_apply_dir(root, of_overlay_dir, true);
 
+	if (*of_overlay_dir == '\0')
+		return 0;
+
 	dir = concat_path_file(of_overlay_basedir, of_overlay_dir);
 
 	ret = of_overlay_apply_dir(root, dir, true);
-- 
2.30.2