[PATCH net-next 4/8] net: phy: realtek: disable SGMII in-band AN for 2.5G PHYs

Daniel Golle
2023-05-10T23:00:12Z

MAC drivers don't use SGMII in-band autonegotiation unless told to do so
in device tree using 'managed = "in-band-status"'. When using MDIO to
access a PHY, in-band-status is unneeded as we have link-status via
MDIO. Switch off SGMII in-band autonegotiation using magic values.

Reported-by: Chen Minqiang <ptpt52@gmail.com>
Reported-by: Chukun Pan <amadeus@jmu.edu.cn>
Reported-by: Yevhen Kolomeiko <jarvis2709@gmail.com>
Tested-by: Yevhen Kolomeiko <jarvis2709@gmail.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
drivers/net/phy/realtek.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
index 0cf7846c9812..acadb6f0057b 100644
--- a/drivers/net/phy/realtek.c
+++ b/drivers/net/phy/realtek.c
@@ -666,7 +666,7 @@ static int rtl822x_get_features(struct phy_device *phydev)

static int rtl822x_config_aneg(struct phy_device *phydev)
{
- int ret = 0;
+ int val, ret = 0;

if (phydev->autoneg == AUTONEG_ENABLE) {
u16 adv2500 = 0;
@@ -681,6 +681,19 @@ static int rtl822x_config_aneg(struct phy_device *phydev)
return ret;
}

+ /* MACs using phylink assume SGMII in-band status is not used.
+ * Keep things as they are for MACs not using phylink such as
+ * RealTek PCIe chips which come with built-in PHYs
+ */
+ if (phydev->phylink) {
+ /* Disable SGMII AN */
+ phy_write_mmd(phydev, RTL8221B_MMD_SERDES_CTRL, 0x7588, 0x2);
+ phy_write_mmd(phydev, RTL8221B_MMD_SERDES_CTRL, 0x7589, 0x71d0);
+ phy_write_mmd(phydev, RTL8221B_MMD_SERDES_CTRL, 0x7587, 0x3);
+ phy_read_mmd_poll_timeout(phydev, RTL8221B_MMD_SERDES_CTRL, 0x7587,
+ val, !(val & BIT(0)), 500, 100000, false);
+ }
+
return __genphy_config_aneg(phydev, ret);
}

--
2.40.0