net: ravb: Make write access to CXR35 first before accessing other EMAC registers

[ Upstream commit d78c0ced60d5e2f8b5a4a0468a5c400b24aeadf2 ]

Hardware manual of RZ/G3S (and RZ/G2L) specifies the following on the
description of CXR35 register (chapter "PHY interface select register
(CXR35)"): "After release reset, make write-access to this register before
making write-access to other registers (except MDIOMOD). Even if not need
to change the value of this register, make write-access to this register
at least one time. Because RGMII/MII MODE is recognized by accessing this
register".

The setup procedure for EMAC module (chapter "Setup procedure" of RZ/G3S,
RZ/G2L manuals) specifies the E-MAC.CXR35 register is the first EMAC
register that is to be configured.

Note [A] from chapter "PHY interface select register (CXR35)" specifies
the following:
[A] The case which CXR35 SEL_XMII is used for the selection of RGMII/MII
in APB Clock 100 MHz.
(1) To use RGMII interface, Set ‘H’03E8_0000’ to this register.
(2) To use MII interface, Set ‘H’03E8_0002’ to this register.

Take into account these indication.

Fixes: 1089877ada8d ("ravb: Add RZ/G2L MII interface support")
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 0cfa1d0..3dab9ea 100644 (file)
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -517,6 +517,15 @@ static void ravb_emac_init_gbeth(struct net_device *ndev)
 {
        struct ravb_private *priv = netdev_priv(ndev);
 
+       if (priv->phy_interface == PHY_INTERFACE_MODE_MII) {
+               ravb_write(ndev, (1000 << 16) | CXR35_SEL_XMII_MII, CXR35);
+               ravb_modify(ndev, CXR31, CXR31_SEL_LINK0 | CXR31_SEL_LINK1, 0);
+       } else {
+               ravb_write(ndev, (1000 << 16) | CXR35_SEL_XMII_RGMII, CXR35);
+               ravb_modify(ndev, CXR31, CXR31_SEL_LINK0 | CXR31_SEL_LINK1,
+                           CXR31_SEL_LINK0);
+       }
+
        /* Receive frame limit set register */
        ravb_write(ndev, GBETH_RX_BUFF_MAX + ETH_FCS_LEN, RFLR);
 
@@ -539,14 +548,6 @@ static void ravb_emac_init_gbeth(struct net_device *ndev)
 
        /* E-MAC interrupt enable register */
        ravb_write(ndev, ECSIPR_ICDIP, ECSIPR);
-
-       if (priv->phy_interface == PHY_INTERFACE_MODE_MII) {
-               ravb_modify(ndev, CXR31, CXR31_SEL_LINK0 | CXR31_SEL_LINK1, 0);
-               ravb_write(ndev, (1000 << 16) | CXR35_SEL_XMII_MII, CXR35);
-       } else {
-               ravb_modify(ndev, CXR31, CXR31_SEL_LINK0 | CXR31_SEL_LINK1,
-                           CXR31_SEL_LINK0);
-       }
 }
 
 static void ravb_emac_init_rcar(struct net_device *ndev)