netdev - [PATCH net-next 1/7] net: dsa: felix: stop writing to read-only fields in MII

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Date:   Thu, 25 Jun 2020 18:23:25 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     davem@...emloft.net, netdev@...r.kernel.org
Cc:     andrew@...n.ch, f.fainelli@...il.com, vivien.didelot@...il.com,
        claudiu.manoil@....com, alexandru.marginean@....com,
        ioana.ciornei@....com, linux@...linux.org.uk
Subject: [PATCH net-next 1/7] net: dsa: felix: stop writing to read-only fields in MII_BMCR

From: Vladimir Oltean <vladimir.oltean@....com>

It looks like BMCR_SPEED and BMCR_DUPLEX are read-only, since they are
actually configured through the vendor-specific IF_MODE (0x14) register.
So, don't perform bogus writes to these fields, giving the impression
that those writes do something.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 drivers/net/dsa/ocelot/felix_vsc9959.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index 2067776773f7..3269c76b59ff 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -845,10 +845,7 @@ static void vsc9959_pcs_init_sgmii(struct phy_device *pcs,
 			  ENETC_PCS_IF_MODE_SGMII_EN |
 			  ENETC_PCS_IF_MODE_SGMII_SPEED(speed));
 
-		/* Yes, not a mistake: speed is given by IF_MODE. */
-		phy_write(pcs, MII_BMCR, BMCR_RESET |
-					 BMCR_SPEED1000 |
-					 BMCR_FULLDPLX);
+		phy_write(pcs, MII_BMCR, BMCR_RESET);
 	}
 }
 
@@ -882,9 +879,7 @@ static void vsc9959_pcs_init_2500basex(struct phy_device *pcs,
 		  ENETC_PCS_IF_MODE_SGMII_EN |
 		  ENETC_PCS_IF_MODE_SGMII_SPEED(ENETC_PCS_SPEED_2500));
 
-	phy_write(pcs, MII_BMCR, BMCR_SPEED1000 |
-				 BMCR_FULLDPLX |
-				 BMCR_RESET);
+	phy_write(pcs, MII_BMCR, BMCR_RESET);
 }
 
 static void vsc9959_pcs_init_usxgmii(struct phy_device *pcs,
-- 
2.25.1