[PATCH net] net: mvneta: fix use of state->speed

[PATCH net] net: mvneta: fix use of state->speed

[Russell King]

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>
---
 drivers/net/ethernet/marvell/mvneta.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index c639e3a29302..7d5d9d34f4e4 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3959,7 +3959,7 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	/* 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->phy_interface != state->interface) {
-- 
2.20.1

Re: [PATCH net] net: mvneta: fix use of state->speed

[David Miller]

From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Tue, 30 Jun 2020 11:04:40 +0100

> 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>

Applied and queued up for -stable, thanks.