net: dsa: microchip: Correct initialization order for KSZ88x3 ports

Adjust the initialization sequence of KSZ88x3 switches to enable
802.1p priority control on Port 2 before configuring Port 1. This
change ensures the apptrust functionality on Port 1 operates
correctly, as it depends on the priority settings of Port 2. The
prior initialization sequence incorrectly configured Port 1 first,
which could lead to functional discrepancies.

Fixes: a1ea57710c9d ("net: dsa: microchip: dcb: add special handling for KSZ88X3 family")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Hariprasad Kelam <hkelam@marvell.com>
Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Link: https://lore.kernel.org/r/20240517050121.2174412-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/dsa/microchip/ksz_dcb.c b/drivers/net/dsa/microchip/ksz_dcb.c
index a9710632756299d9e33bf63116c49ed5a09e0d60..086bc9b3cf5362196be609f052bb3c4fc848ae61 100644 (file)
--- a/drivers/net/dsa/microchip/ksz_dcb.c
+++ b/drivers/net/dsa/microchip/ksz_dcb.c
@@ -805,5 +805,15 @@ int ksz_dcb_init(struct ksz_device *dev)
        if (ret)
                return ret;
 
+       /* Enable 802.1p priority control on Port 2 during switch initialization.
+        * This setup is critical for the apptrust functionality on Port 1, which
+        * relies on the priority settings of Port 2. Note: Port 1 is naturally
+        * configured before Port 2, necessitating this configuration order.
+        */
+       if (ksz_is_ksz88x3(dev))
+               return ksz_prmw8(dev, KSZ_PORT_2, KSZ8_REG_PORT_1_CTRL_0,
+                                KSZ8_PORT_802_1P_ENABLE,
+                                KSZ8_PORT_802_1P_ENABLE);
+
        return 0;
 }