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From:   David Yang <mmyangfl@gmail.com>
To:     mmyangfl@gmail.com
Cc:     Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] net: mv643xx_eth: support MII/GMII/RGMII modes
Date:   Sat,  1 Oct 2022 03:49:23 +0800
Message-Id: <20220930194923.954551-1-mmyangfl@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

On device reset all ports are automatically set to RGMII mode. MII
mode must be explicitly enabled.

If SoC has two Ethernet controllers, by setting both of them into MII
mode, the first controller enters GMII mode, while the second
controller is effectively disabled. This requires configuring (and
maybe enabling) the second controller in the device tree, even though
it cannot be used.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 drivers/net/ethernet/marvell/mv643xx_eth.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
index b6be0552a..e2216ce5e 100644
--- a/drivers/net/ethernet/marvell/mv643xx_eth.c
+++ b/drivers/net/ethernet/marvell/mv643xx_eth.c
@@ -108,6 +108,7 @@ static char mv643xx_eth_driver_version[] = "1.4";
 #define TXQ_COMMAND			0x0048
 #define TXQ_FIX_PRIO_CONF		0x004c
 #define PORT_SERIAL_CONTROL1		0x004c
+#define  RGMII_EN			0x00000008
 #define  CLK125_BYPASS_EN		0x00000010
 #define TX_BW_RATE			0x0050
 #define TX_BW_MTU			0x0058
@@ -1245,6 +1246,21 @@ static void mv643xx_eth_adjust_link(struct net_device *dev)
 
 out_write:
 	wrlp(mp, PORT_SERIAL_CONTROL, pscr);
+
+	/* If two Ethernet controllers present in the SoC, MII modes follow the
+	 * following matrix:
+	 *
+	 * Port0 Mode	Port1 Mode	Port0 RGMII_EN	Port1 RGMII_EN
+	 * RGMII	RGMII		1		1
+	 * RGMII	MII/MMII	1		0
+	 * MII/MMII	RGMII		0		1
+	 * GMII		N/A		0		0
+	 *
+	 * To enable GMII on Port 0, Port 1 must also disable RGMII_EN too.
+	 */
+	if (!phy_interface_is_rgmii(dev->phydev))
+		wrlp(mp, PORT_SERIAL_CONTROL1,
+		     rdlp(mp, PORT_SERIAL_CONTROL1) & ~RGMII_EN);
 }
 
 /* statistics ***************************************************************/
-- 
2.35.1