[PATCH net-next 3/6] net: stmmac: start phylink before setting up hardware

[Clément Léger]

The stmmac on the Renesas RZ/N1 platform is connected to the PCS which
must be configured to provide a correct RGMII RX clock to the stmmac IP.
Without the RX clock, the driver will fail to initialize the hardware
(more specifically, the driver will report it fails to reset DMA). In
order to fix that, start phylink mecanism before setting up hardware.

Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index f2247b8cf0a3..88c941003855 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3818,6 +3818,12 @@ static int __stmmac_open(struct net_device *dev,
 		}
 	}
 
+	/* We need to setup the phy & PCS before accessing the stmmac registers
+	 * because in some cases (RZ/N1), if the stmmac IP is not clocked by the
+	 * PCS, hardware init will fail because it lacks a RGMII RX clock.
+	 */
+	phylink_start(priv->phylink);
+
 	ret = stmmac_hw_setup(dev, true);
 	if (ret < 0) {
 		netdev_err(priv->dev, "%s: Hw setup failed\n", __func__);
@@ -3826,7 +3832,6 @@ static int __stmmac_open(struct net_device *dev,
 
 	stmmac_init_coalesce(priv);
 
-	phylink_start(priv->phylink);
 	/* We may have called phylink_speed_down before */
 	phylink_speed_up(priv->phylink);
 
-- 
2.39.0