openwrt/target/linux/generic/backport-6.6/711-v6.8-01-net-phy-at803x-generalize-cdt-fault-length-function.patch

From 22eb276098da820d9440fad22901f9b74ed4d659 Mon Sep 17 00:00:00 2001
From: Christian Marangi <ansuelsmth@gmail.com>
Date: Thu, 4 Jan 2024 22:30:38 +0100
Subject: [PATCH 1/4] net: phy: at803x: generalize cdt fault length function

Generalize cable test fault length function since they all base on the
same magic values (already reverse engineered to understand the meaning
of it) to have consistenct values on every PHY.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/phy/at803x.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -1192,10 +1192,8 @@ static bool at803x_cdt_fault_length_vali
 	return false;
 }
 
-static int at803x_cdt_fault_length(u16 status)
+static int at803x_cdt_fault_length(int dt)
 {
-	int dt;
-
 	/* According to the datasheet the distance to the fault is
 	 * DELTA_TIME * 0.824 meters.
 	 *
@@ -1211,8 +1209,6 @@ static int at803x_cdt_fault_length(u16 s
 	 * With a VF of 0.69 we get the factor 0.824 mentioned in the
 	 * datasheet.
 	 */
-	dt = FIELD_GET(AT803X_CDT_STATUS_DELTA_TIME_MASK, status);
-
 	return (dt * 824) / 10;
 }
 
@@ -1265,9 +1261,11 @@ static int at803x_cable_test_one_pair(st
 	ethnl_cable_test_result(phydev, ethtool_pair[pair],
 				at803x_cable_test_result_trans(val));
 
-	if (at803x_cdt_fault_length_valid(val))
+	if (at803x_cdt_fault_length_valid(val)) {
+		val = FIELD_GET(AT803X_CDT_STATUS_DELTA_TIME_MASK, val);
 		ethnl_cable_test_fault_length(phydev, ethtool_pair[pair],
 					      at803x_cdt_fault_length(val));
+	}
 
 	return 1;
 }
@@ -1992,7 +1990,8 @@ static int qca808x_cdt_fault_length(stru
 	if (val < 0)
 		return val;
 
-	return (FIELD_GET(QCA808X_CDT_DIAG_LENGTH, val) * 824) / 10;
+	val = FIELD_GET(QCA808X_CDT_DIAG_LENGTH, val);
+	return at803x_cdt_fault_length(val);
 }
 
 static int qca808x_cable_test_start(struct phy_device *phydev)