[PATCH] clk: handle get_parent callbacks returning an error

[Ahmad Fatoum <a.fatoum@barebox.org>]

A mux with a value table returns -EINVAL from get_parent when the
register holds a value missing from the table. clk_get_parent() only
rejected indices >= num_parents, so -EINVAL went on to index the
parents array as u8 234 and clk_dump crashed on the Amlogic G12 clock
controller.

Let's return -ENODEV for negative indices as well.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 drivers/clk/clk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 99f995fb0224..1d6aaa46d9b1 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -382,7 +382,8 @@ struct clk *clk_get_parent(struct clk *clk)
 
 		idx = clk->ops->get_parent(hw);
 
-		if (idx >= clk->num_parents)
+		/* an error means the register selects no known parent */
+		if (idx < 0 || idx >= clk->num_parents)
 			return ERR_PTR(-ENODEV);
 	} else {
 		idx = 0;
-- 
2.47.3