of_clk_get_by_name() returns error pointers instead of NULL. Use IS_ERR() checks the return value to catch errors. Fixes: 836fb30949d9 ("soc: imx8m: Enable OCOTP clock before reading the register") Signed-off-by: Miaoqian Lin <linmq006@gmail.com> Signed-off-by: Shawn Guo <shawnguo@kernel.org>