From 7289d42b8fd17713531c0f7e8ae7653d1f2c6f8f Mon Sep 17 00:00:00 2001
From: Frank Wunderlich <frank-w@public-files.de>
Date: Thu, 9 Apr 2026 15:33:42 +0200
Subject: [PATCH] net: pcs: pcs-mtk-lynxi: fix bpi-r3 serdes configuration

Commit 8871389da151 introduces common pcs dts properties which writes
rx=normal,tx=normal polarity to register SGMSYS_QPHY_WRAP_CTRL of switch.
This is initialized with tx-bit set and so change inverts polarity
compared to before.

It looks like mt7531 has tx polarity inverted in hardware and set tx-bit
by default to restore the normal polarity.

Till this patch the register write was only called when mediatek,pnswap
property was set which cannot be done for switch because the fw-node param
was always NULL from switch driver in the mtk_pcs_lynxi_create call.

Do not configure switch side like it's done before.

Fixes: 8871389da151 ("net: pcs: pcs-mtk-lynxi: deprecate "mediatek,pnswap"")
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
---
 drivers/net/pcs/pcs-mtk-lynxi.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/pcs/pcs-mtk-lynxi.c
+++ b/drivers/net/pcs/pcs-mtk-lynxi.c
@@ -129,6 +129,9 @@ static int mtk_pcs_config_polarity(struc
 	unsigned int val = 0;
 	int ret;
 
+	if (!fwnode)
+		return 0;
+
 	if (fwnode_property_read_bool(fwnode, "mediatek,pnswap"))
 		default_pol = PHY_POL_INVERT;
 
