[PATCH net-next v4 7/7] net: dsa: microchip: Disable PTP function of KSZ8463

[<Tristram.Ha@microchip.com>]

From: Tristram Ha <tristram.ha@microchip.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.

Note the PTP driver for KSZ switches does not work for KSZ8463 and is not
activated for it.

Signed-off-by: Tristram Ha <tristram.ha@microchip.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 1fb0ebd0c50d..59e7960a754d 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