netdev - [PATCH net-next v2 3/3] net: phy: dp83td510: disable cable test support for 1Vpp PHYs

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Message-Id: <20220608071749.3818602-4-o.rempel@pengutronix.de>
Date:   Wed,  8 Jun 2022 09:17:49 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Oleksij Rempel <o.rempel@...gutronix.de>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH net-next v2 3/3] net: phy: dp83td510: disable cable test support for 1Vpp PHYs

Using 1Vpp pulse provides most unreliable results. So, disable cable
testing if PHY is bootstrapped to use 1Vpp-only mode.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/net/phy/dp83td510.c | 52 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/dp83td510.c b/drivers/net/phy/dp83td510.c
index de32ab1a262d..1eaf2ceaca8c 100644
--- a/drivers/net/phy/dp83td510.c
+++ b/drivers/net/phy/dp83td510.c
@@ -31,6 +31,8 @@
 #define DP83TD510E_TDR_FAIL			BIT(0)
 
 #define DP83TD510E_TDR_CFG1			0x300
+/* TX_TYPE: Transmit voltage level for TDR. 0 = 1V, 1 = 2.4V */
+#define DP83TD510E_TDR_TX_TYPE			BIT(12)
 
 #define DP83TD510E_TDR_CFG2			0x301
 #define DP83TD510E_TDR_END_TAP_INDEX_1		GENMASK(14, 8)
@@ -71,6 +73,10 @@
 #define DP83TD510E_UNKN_0310			0x310
 #define DP83TD510E_0310_VAL			0x0036
 
+#define DP83TD510E_CHIP_SOR_1			0x467
+/* If LED_2 is set, blacklist 2.4V mode */
+#define DP83TD510E_SOR_LED_2			BIT(7)
+
 #define DP83TD510E_AN_STAT_1			0x60c
 #define DP83TD510E_MASTER_SLAVE_RESOL_FAIL	BIT(15)
 
@@ -78,6 +84,10 @@
 
 #define DP83TD510_SQI_MAX	7
 
+struct dp83td510_priv {
+	bool allow_v2_4_mode;
+};
+
 /* Register values are converted to SNR(dB) as suggested by
  * "Application Report - DP83TD510E Cable Diagnostics Toolkit":
  * SNR(dB) = -10 * log10 (VAL/2^17) - 1.76 dB.
@@ -308,12 +318,29 @@ static int dp83td510_tdr_init(struct phy_device *phydev)
 
 static int dp83td510_cable_test_start(struct phy_device *phydev)
 {
-	int ret;
+	struct dp83td510_priv *priv = phydev->priv;
+	int ret, cfg = 0;
+
+	/* Generate 2.4Vpp pulse if HW is allowed to do so */
+	if (priv->allow_v2_4_mode) {
+		cfg |= DP83TD510E_TDR_TX_TYPE;
+	} else {
+		/* This PHY do not provide usable results with 1Vpp pulse.
+		 * Potentially different dp83td510_tdr_init() values are
+		 * needed.
+		 */
+		return -EOPNOTSUPP;
+	}
 
 	ret = dp83td510_tdr_init(phydev);
 	if (ret)
 		return ret;
 
+	ret = phy_modify_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_TDR_CFG1,
+			     DP83TD510E_TDR_TX_TYPE, cfg);
+	if (ret)
+		return ret;
+
 	return phy_set_bits_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_TDR_CFG,
 				DP83TD510E_TDR_START);
 }
@@ -369,6 +396,28 @@ static int dp83td510_cable_test_get_status(struct phy_device *phydev,
 	return phy_set_bits(phydev, MII_BMCR, BMCR_RESET);
 }
 
+static int dp83td510_probe(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	struct dp83td510_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	phydev->priv = priv;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TD510E_CHIP_SOR_1);
+	if (ret < 0)
+		return ret;
+
+	if (!(ret & DP83TD510E_SOR_LED_2))
+		priv->allow_v2_4_mode = true;
+
+	return 0;
+}
+
 static int dp83td510_get_features(struct phy_device *phydev)
 {
 	/* This PHY can't respond on MDIO bus if no RMII clock is enabled.
@@ -393,6 +442,7 @@ static struct phy_driver dp83td510_driver[] = {
 	.name		= "TI DP83TD510E",
 
 	.flags          = PHY_POLL_CABLE_TEST,
+	.probe		= dp83td510_probe,
 	.config_aneg	= dp83td510_config_aneg,
 	.read_status	= dp83td510_read_status,
 	.get_features	= dp83td510_get_features,
-- 
2.30.2