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From: Oleksij Rempel <o.rempel@pengutronix.de>
To: "David S. Miller" <davem@davemloft.net>,
	Andrew Lunn <andrew@lunn.ch>,
	Eric Dumazet <edumazet@google.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Vladimir Oltean <olteanv@gmail.com>,
	Woojung Huh <woojung.huh@microchip.com>,
	Arun Ramadoss <arun.ramadoss@microchip.com>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>,
	kernel@pengutronix.de,
	linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org,
	UNGLinuxDriver@microchip.com,
	David Ahern <dsahern@kernel.org>,
	Simon Horman <horms@kernel.org>,
	Willem de Bruijn <willemb@google.com>,
	=?UTF-8?q?S=C3=B8ren=20Andersen?= <san@skov.dk>
Subject: [PATCH net v1 1/1] net: dsa: microchip: Correct initialization order for KSZ88x3 ports
Date: Thu, 16 May 2024 09:08:52 +0200
Message-Id: <20240516070852.1953381-1-o.rempel@pengutronix.de>
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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>
---
 drivers/net/dsa/microchip/ksz_dcb.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz_dcb.c b/drivers/net/dsa/microchip/ksz_dcb.c
index a971063275629..19b228b849247 100644
--- a/drivers/net/dsa/microchip/ksz_dcb.c
+++ b/drivers/net/dsa/microchip/ksz_dcb.c
@@ -805,5 +805,18 @@ 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)) {
+		ret = ksz_prmw8(dev, KSZ_PORT_2, KSZ8_REG_PORT_1_CTRL_0,
+				KSZ8_PORT_802_1P_ENABLE,
+				KSZ8_PORT_802_1P_ENABLE);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
-- 
2.39.2