[U-Boot] [RFC v2] drivers: net: phy: atheros: apply the previous register setting for AR8031 to fix the voltage peak issue

[Ken Lin <yungching0725@gmail.com>]

Apply the previous setting for the reserved bits in SetDes Test and System Mode Control register
to avoid the voltage peak issue while we do the IEEE PHY comformance test

Tested on Advantech DMS-BA16 board
Tested-by: Ken Lin <ken.lin@advantech.com>
Signed-off-by: Ken Lin <ken.lin@advantech.com>
---
 drivers/net/phy/atheros.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/phy/atheros.c b/drivers/net/phy/atheros.c
index b34cdd3d87..87e8fc55d4 100644
--- a/drivers/net/phy/atheros.c
+++ b/drivers/net/phy/atheros.c
@@ -17,6 +17,8 @@
 #define AR803x_DEBUG_REG_0		0x0
 #define AR803x_RGMII_RX_CLK_DLY		0x8000
 
+#define AR803x_SERDES_TEST_DEFAULT	0x3C47
+
 static int ar8021_config(struct phy_device *phydev)
 {
 	phy_write(phydev, MDIO_DEVAD_NONE, 0x1d, 0x05);
@@ -28,6 +30,8 @@ static int ar8021_config(struct phy_device *phydev)
 
 static int ar8031_config(struct phy_device *phydev)
 {
+	int regval;
+
 	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
 	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) {
 		phy_write(phydev, MDIO_DEVAD_NONE, AR803x_PHY_DEBUG_ADDR_REG,
@@ -44,6 +48,10 @@ static int ar8031_config(struct phy_device *phydev)
 			  AR803x_RGMII_RX_CLK_DLY);
 	}
 
+        phy_write(phydev, MDIO_DEVAD_NONE, AR803x_PHY_DEBUG_ADDR_REG, AR803x_DEBUG_REG_5);
+        regval = phy_read(phydev, MDIO_DEVAD_NONE, AR803x_PHY_DEBUG_DATA_REG);
+        phy_write(phydev, MDIO_DEVAD_NONE, AR803x_PHY_DEBUG_DATA_REG, regval | AR803x_SERDES_TEST_DEFAULT);
+
 	phydev->supported = phydev->drv->features;
 
 	genphy_config_aneg(phydev);
-- 
2.11.0