linux-kernel - [PATCH v2] net: phy: dp83822: Fix RGMII TX delay configuration

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Date: Sun,  4 Feb 2024 11:11:28 +0100
From: Tim Pambor <tp@...systeme.de>
To: Andrew Lunn <andrew@...n.ch>
Cc: 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>,
	Dan Murphy <dmurphy@...com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Tim Pambor <tp@...systeme.de>
Subject: [PATCH v2] net: phy: dp83822: Fix RGMII TX delay configuration

The logic for enabling the TX clock shift is inverse of enabling the RX
clock shift. The TX clock shift is disabled when DP83822_TX_CLK_SHIFT is
set. Correct the current behavior and always write the delay configuration
to ensure consistent delay settings regardless of bootloader configuration.

Reference: https://www.ti.com/lit/ds/symlink/dp83822i.pdf p. 69

Fixes: 8095295292b5 ("net: phy: DP83822: Add setting the fixed internal delay")
Signed-off-by: Tim Pambor <tp@...systeme.de>
---
Changes in v2:
  - Further cleanup of RGMII configuration
  - Check for errors setting DP83822_RGMII_MODE_EN
---
 drivers/net/phy/dp83822.c | 41 +++++++++++++--------------------------
 1 file changed, 14 insertions(+), 27 deletions(-)

diff --git a/drivers/net/phy/dp83822.c b/drivers/net/phy/dp83822.c
index b7cb71817780..1b2c34a97396 100644
--- a/drivers/net/phy/dp83822.c
+++ b/drivers/net/phy/dp83822.c
@@ -380,42 +380,29 @@ static int dp83822_config_init(struct phy_device *phydev)
 {
 	struct dp83822_private *dp83822 = phydev->priv;
 	struct device *dev = &phydev->mdio.dev;
-	int rgmii_delay;
-	s32 rx_int_delay;
-	s32 tx_int_delay;
+	int rcsr_mask = DP83822_RGMII_MODE_EN;
+	int rcsr = 0;
 	int err = 0;
 	int bmcr;
 
 	if (phy_interface_is_rgmii(phydev)) {
-		rx_int_delay = phy_get_internal_delay(phydev, dev, NULL, 0,
-						      true);
+		rcsr |= DP83822_RGMII_MODE_EN;
 
-		if (rx_int_delay <= 0)
-			rgmii_delay = 0;
-		else
-			rgmii_delay = DP83822_RX_CLK_SHIFT;
+		/* Set DP83822_RX_CLK_SHIFT to enable rx clk internal delay */
+		if (phy_get_internal_delay(phydev, dev, NULL, 0, true) > 0)
+			rcsr |= DP83822_RX_CLK_SHIFT;
 
-		tx_int_delay = phy_get_internal_delay(phydev, dev, NULL, 0,
-						      false);
-		if (tx_int_delay <= 0)
-			rgmii_delay &= ~DP83822_TX_CLK_SHIFT;
-		else
-			rgmii_delay |= DP83822_TX_CLK_SHIFT;
+		/* Set DP83822_TX_CLK_SHIFT to disable tx clk internal delay */
+		if (phy_get_internal_delay(phydev, dev, NULL, 0, false) <= 0)
+			rcsr |= DP83822_TX_CLK_SHIFT;
 
-		if (rgmii_delay) {
-			err = phy_set_bits_mmd(phydev, DP83822_DEVADDR,
-					       MII_DP83822_RCSR, rgmii_delay);
-			if (err)
-				return err;
-		}
-
-		phy_set_bits_mmd(phydev, DP83822_DEVADDR,
-					MII_DP83822_RCSR, DP83822_RGMII_MODE_EN);
-	} else {
-		phy_clear_bits_mmd(phydev, DP83822_DEVADDR,
-					MII_DP83822_RCSR, DP83822_RGMII_MODE_EN);
+		rcsr_mask |= DP83822_RX_CLK_SHIFT | DP83822_TX_CLK_SHIFT;
 	}
 
+	err = phy_modify_mmd(phydev, DP83822_DEVADDR, MII_DP83822_RCSR, rcsr_mask, rcsr);
+	if (err < 0)
+		return err;
+
 	if (dp83822->fx_enabled) {
 		err = phy_modify(phydev, MII_DP83822_CTRL_2,
 				 DP83822_FX_ENABLE, 1);
-- 
2.43.0