[PATCH net 3/5] net: stmmac: Signal to PHY/PCS drivers to keep RX clock on

[Romain Gantois]

From: Russell King <linux at armlinux.org.uk>

There is a reocurring issue with stmmac controllers where the MAC fails to
initialize its hardware if an RX clock signal isn't provided on the MAC/PHY
link.

This causes issues when PHY or PCS devices either go into suspend while
cutting the RX clock or do not bring the clock signal up early enough for
the MAC to initialize successfully.

Set the mac_requires_rxc flag in the stmmac phylink config so that PHY/PCS
drivers know to keep the RX clock up at all times.

Reported-by: Clark Wang <xiaoning.wang at nxp.com>
Link: https://lore.kernel.org/all/20230202081559.3553637-1-xiaoning.wang@nxp.com/
Reported-by: Clément Léger <clement.leger at bootlin.com>
Link: https://lore.kernel.org/linux-arm-kernel/20230116103926.276869-4-clement.leger@bootlin.com/
Signed-off-by: Russell King <linux at armlinux.org.uk>
[rgantois: commit log]
Signed-off-by: Romain Gantois <romain.gantois at bootlin.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 37e64283f910..ffecc28de234 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1221,6 +1221,11 @@ static int stmmac_phy_setup(struct stmmac_priv *priv)
 	priv->phylink_config.type = PHYLINK_NETDEV;
 	priv->phylink_config.mac_managed_pm = true;
 
+	/* stmmac always requires a receive clock in order for things like
+	 * hardware reset to work.
+	 */
+	priv->phylink_config.mac_requires_rxc = true;
+
 	mdio_bus_data = priv->plat->mdio_bus_data;
 	if (mdio_bus_data)
 		priv->phylink_config.ovr_an_inband =
-- 
2.43.0