net: phy: air_an8801: ensure maximum available speed link use

To ensure that the Airoha AN8801R PHY uses the maximum available link
speed, an additional register write is needed to configure the function
mode for either 1G or 100M/10M operation after link detection.

So, in air_an8801 driver, implement a custom read_status callback, that
after genphy_read_status determines the link speed, sets the bit 0 of
the link mode register (REG_LINK_MODE) if the detected speed is 1Gbps,
or unsets it otherwise.

Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260526-add-airoha-an8801-support-v5-6-01aea8dee69b@collabora.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/air_an8801.c b/drivers/net/phy/air_an8801.c
index aa24bb182d64522610449a78ed2f5634e5b490f3..f97c78e430237e4645129d19249ff5503d6a58aa 100644 (file)
--- a/drivers/net/phy/air_an8801.c
+++ b/drivers/net/phy/air_an8801.c
@@ -996,6 +996,41 @@ static int an8801r_config_init(struct phy_device *phydev)
        return 0;
 }
 
+static int an8801r_read_status(struct phy_device *phydev)
+{
+       int prev_speed, ret;
+       u32 val;
+
+       prev_speed = phydev->speed;
+
+       ret = genphy_read_status(phydev);
+       if (ret)
+               return ret;
+
+       if (!phydev->link) {
+               phydev->speed = SPEED_UNKNOWN;
+               return 0;
+       }
+
+       if (prev_speed != phydev->speed) {
+               /* Ensure that PHY switches to 1G speed when available,
+                * by configuring the function mode for either 1G or 100M/10M
+                * operation.
+                * Therefore, set the link mode register, after read_status
+                * determines the link speed.
+                */
+               val = phydev->speed == SPEED_1000 ?
+                     AN8801_BPBUS_LINK_MODE_1000 : 0;
+
+               return an8801_buckpbus_reg_rmw(phydev,
+                                              AN8801_BPBUS_REG_LINK_MODE,
+                                              AN8801_BPBUS_LINK_MODE_1000,
+                                              val);
+       }
+
+       return 0;
+}
+
 static int an8801r_probe(struct phy_device *phydev)
 {
        struct device *dev = &phydev->mdio.dev;
@@ -1093,6 +1128,7 @@ static struct phy_driver airoha_driver[] = {
        .suspend                = an8801r_suspend,
        .resume                 = an8801r_resume,
        .config_aneg            = genphy_config_aneg,
+       .read_status            = an8801r_read_status,
        .config_intr            = an8801r_config_intr,
        .handle_interrupt       = an8801r_handle_interrupt,
        .set_wol                = an8801r_set_wol,