From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Tue, 30 Jun 2020 11:04:40 +0100
Subject: net: mvneta: fix use of state->speed
Git-commit: f2ca673d2cd5df9a76247b670e9ffd4d63682b3f
Patch-mainline: 5.8-rc5
References: networking-stable-20_07_17

When support for short preambles was added, it incorrectly keyed its
decision off state->speed instead of state->interface.  state->speed
is not guaranteed to be correct for in-band modes, which can lead to
short preambles being unexpectedly disabled.

Fix this by keying off the interface mode, which is the only way that
mvneta can operate at 2.5Gbps.

Fixes: da58a931f248 ("net: mvneta: Add support for 2500Mbps SGMII")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/net/ethernet/marvell/mvneta.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3556,7 +3556,7 @@ static void mvneta_mac_config(struct phy
 	/* When at 2.5G, the link partner can send frames with shortened
 	 * preambles.
 	 */
-	if (state->speed == SPEED_2500)
+	if (state->interface == PHY_INTERFACE_MODE_2500BASEX)
 		new_ctrl4 |= MVNETA_GMAC4_SHORT_PREAMBLE_ENABLE;
 
 	if (pp->comphy && pp->phy_interface != state->interface &&