[PATCH v2] net: sh_eth: fix a missing check of of_get_phy_mode

[Kangjie Lu <kjlu@umn.edu>]

of_get_phy_mode may fail and return a negative error code;
the fix checks the return value of of_get_phy_mode and
returns NULL of it fails.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/net/ethernet/renesas/sh_eth.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 239eeafe1b2d..e33af371b169 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -3181,14 +3181,16 @@ static struct sh_eth_plat_data *sh_eth_parse_dt(struct device *dev)
 	struct device_node *np = dev->of_node;
 	struct sh_eth_plat_data *pdata;
 	const char *mac_addr;
+	int ret;
 
 	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
 		return NULL;
 
-	pdata->phy_interface = of_get_phy_mode(np);
-	if (pdata->phy_interface < 0)
+	ret = of_get_phy_mode(np);
+	if (ret < 0)
 		return NULL;
+	pdata->phy_interface = ret;
 
 	mac_addr = of_get_mac_address(np);
 	if (mac_addr)
-- 
2.17.1