netdev - [PATCH net-next v3 7/7] net: dsa: microchip: Disable PTP function of KSZ8463

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Message-ID: <20250709003234.50088-8-Tristram.Ha@microchip.com>
Date: Tue, 8 Jul 2025 17:32:33 -0700
From: <Tristram.Ha@...rochip.com>
To: Woojung Huh <woojung.huh@...rochip.com>, Andrew Lunn <andrew@...n.ch>,
	Vladimir Oltean <olteanv@...il.com>, Rob Herring <robh@...nel.org>,
	"Krzysztof Kozlowski" <krzk+dt@...nel.org>, Conor Dooley
	<conor+dt@...nel.org>
CC: Maxime Chevallier <maxime.chevallier@...tlin.com>, "David S. Miller"
	<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	<kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Marek Vasut
	<marex@...x.de>, <UNGLinuxDriver@...rochip.com>,
	<devicetree@...r.kernel.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Tristram Ha <tristram.ha@...rochip.com>
Subject: [PATCH net-next v3 7/7] net: dsa: microchip: Disable PTP function of KSZ8463

From: Tristram Ha <tristram.ha@...rochip.com>

The PTP function of KSZ8463 is on by default.  However, its proprietary
way of storing timestamp directly in a reserved field inside the PTP
message header is not suitable for use with the current Linux PTP stack
implementation.  It is necessary to disable the PTP function to not
interfere the normal operation of the MAC.

Signed-off-by: Tristram Ha <tristram.ha@...rochip.com>
---
 drivers/net/dsa/microchip/ksz8.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz8.c b/drivers/net/dsa/microchip/ksz8.c
index ddbd05c44ce5..fd4a000487d6 100644
--- a/drivers/net/dsa/microchip/ksz8.c
+++ b/drivers/net/dsa/microchip/ksz8.c
@@ -1761,6 +1761,17 @@ void ksz8_config_cpu_port(struct dsa_switch *ds)
 					   reg16(dev, KSZ8463_REG_DSP_CTRL_6),
 					   COPPER_RECEIVE_ADJUSTMENT, 0);
 		}
+
+		/* Turn off PTP function as the switch's proprietary way of
+		 * handling timestamp is not supported in current Linux PTP
+		 * stack implementation.
+		 */
+		regmap_update_bits(ksz_regmap_16(dev),
+				   reg16(dev, KSZ8463_PTP_MSG_CONF1),
+				   PTP_ENABLE, 0);
+		regmap_update_bits(ksz_regmap_16(dev),
+				   reg16(dev, KSZ8463_PTP_CLK_CTRL),
+				   PTP_CLK_ENABLE, 0);
 	}
 }
 
-- 
2.34.1