linux-kernel - [PATCH net-next 7/9] net: pcs: xpcs: allow lane polarity inversion

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Message-Id: <20251122193341.332324-8-vladimir.oltean@nxp.com>
Date: Sat, 22 Nov 2025 21:33:39 +0200
From: Vladimir Oltean <vladimir.oltean@....com>
To: netdev@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-phy@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	Daniel Golle <daniel@...rotopia.org>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Eric Woudstra <ericwouds@...il.com>,
	Marek Behún <kabel@...nel.org>,
	Lee Jones <lee@...nel.org>,
	Patrice Chotard <patrice.chotard@...s.st.com>
Subject: [PATCH net-next 7/9] net: pcs: xpcs: allow lane polarity inversion

Using the linux/phy/phy-common-props.h helpers, get the 'rx-polarity'
and 'tx-polarity' device tree properties, and apply them to hardware in
the newly introduced xpcs_pma_config(), called from phylink_pcs_ops ::
pcs_config().

This is the right place to do it, as the generic PHY helpers require
knowing the phy_interface_t for which we want the polarity known, and
that comes from phylink.

Default to PHY_POL_NORMAL, and support normal and inverted polarities in
the RX and TX directions.

Note that for SJA1105, 'normal' in the TX direction is inverted in the
PCS, and 'inverted' is 'normal' in the PCS. This is because the device
tree property refers to the effect as visible at the device's pinout.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 drivers/net/pcs/Kconfig    |  1 +
 drivers/net/pcs/pcs-xpcs.c | 33 +++++++++++++++++++++++++++------
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/drivers/net/pcs/Kconfig b/drivers/net/pcs/Kconfig
index ecbc3530e780..3598747d6c53 100644
--- a/drivers/net/pcs/Kconfig
+++ b/drivers/net/pcs/Kconfig
@@ -8,6 +8,7 @@ menu "PCS device drivers"
 config PCS_XPCS
 	tristate "Synopsys DesignWare Ethernet XPCS"
 	select PHYLINK
+	select GENERIC_PHY_COMMON_PROPS
 	help
 	  This module provides a driver and helper functions for Synopsys
 	  DesignWare XPCS controllers.
diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 670441186cc6..7625dc29d2ee 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -11,6 +11,7 @@
 #include <linux/pcs/pcs-xpcs.h>
 #include <linux/mdio.h>
 #include <linux/phy.h>
+#include <linux/phy/phy-common-props.h>
 #include <linux/phylink.h>
 #include <linux/property.h>
 
@@ -810,14 +811,34 @@ static int xpcs_config_2500basex(struct dw_xpcs *xpcs)
 
 static int xpcs_pma_config(struct dw_xpcs *xpcs, const struct dw_xpcs_compat *compat)
 {
+	struct fwnode_handle *fwnode = dev_fwnode(&xpcs->mdiodev->dev);
+	u32 val = 0, mask;
+	int pol;
 	int ret;
 
-	if (xpcs->need_opposite_tx_polarity) {
-		ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL2,
-				 DW_VR_MII_DIG_CTRL2_TX_POL_INV);
-		if (ret)
-			return ret;
-	}
+	mask = DW_VR_MII_DIG_CTRL2_TX_POL_INV | DW_VR_MII_DIG_CTRL2_RX_POL_INV;
+
+	pol = phy_get_rx_polarity(fwnode, phy_modes(compat->interface),
+				  PHY_POL_NORMAL | PHY_POL_INVERT,
+				  PHY_POL_NORMAL);
+	if (pol < 0)
+		return pol;
+	if (pol == PHY_POL_INVERT)
+		val |= DW_VR_MII_DIG_CTRL2_RX_POL_INV;
+
+	pol = phy_get_tx_polarity(fwnode, phy_modes(compat->interface),
+				  PHY_POL_NORMAL | PHY_POL_INVERT,
+				  PHY_POL_NORMAL);
+	if (pol < 0)
+		return pol;
+	if (xpcs->need_opposite_tx_polarity)
+		pol = !pol;
+	if (pol == PHY_POL_INVERT)
+		val |= DW_VR_MII_DIG_CTRL2_TX_POL_INV;
+
+	ret = xpcs_modify(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL2, mask, val);
+	if (ret < 0)
+		return ret;
 
 	if (compat->pma_config) {
 		ret = compat->pma_config(xpcs);
-- 
2.34.1