[PATCH net-next] net: stmmac: failure to probe without MAC interface specified

[Russell King (Oracle)]

Alexander Stein reports that commit a014c35556b9 ("net: stmmac: clarify
difference between "interface" and "phy_interface"") caused breakage,
because plat->mac_interface will never be negative. Fix this by using
the "rc" temporary variable in stmmac_probe_config_dt().

Reported-by: Alexander Stein <alexander.stein at ew.tq-group.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
---
I don't think the net tree is up to date with the net-next, so this
patch needs applying to net-next preferably before the pull request
to fix a regression.

Thanks.

 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 35f4b1484029..0f28795e581c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -419,9 +419,8 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
 		return ERR_PTR(phy_mode);
 
 	plat->phy_interface = phy_mode;
-	plat->mac_interface = stmmac_of_get_mac_mode(np);
-	if (plat->mac_interface < 0)
-		plat->mac_interface = plat->phy_interface;
+	rc = stmmac_of_get_mac_mode(np);
+	plat->mac_interface = rc < 0 ? plat->phy_interface : rc;
 
 	/* Some wrapper drivers still rely on phy_node. Let's save it while
 	 * they are not converted to phylink. */
-- 
2.30.2