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From: Andrew Lunn <andrew@lunn.ch>
To: David Miller <davem@davemloft.net>
Cc: netdev <netdev@vger.kernel.org>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Chris Healy <cphealy@gmail.com>,
	Michal Kubecek <mkubecek@suse.cz>, Andrew Lunn <andrew@lunn.ch>
Subject: [PATCH net-next 7/7] net: phy: marvell: Configure TDR pulse based on measurement length
Date: Sun, 24 May 2020 17:27:47 +0200	[thread overview]
Message-ID: <20200524152747.745893-8-andrew@lunn.ch> (raw)
In-Reply-To: <20200524152747.745893-1-andrew@lunn.ch>

When performing a TDR measurement for a short distance, the pulse
width should be low, to help differentiate between the outgoing pulse
and any reflection. For longer distances, the pulse should be wider,
to help with attenuation.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/phy/marvell.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
index 5edf969978bd..7ec57b8a1aed 100644
--- a/drivers/net/phy/marvell.c
+++ b/drivers/net/phy/marvell.c
@@ -214,6 +214,11 @@
 #define MII_VCT5_TX_PULSE_CTRL_MAX_AMP			BIT(7)
 #define MII_VCT5_TX_PULSE_CTRL_GT_140m_46_86mV		(0x6 << 0)
 
+/* For TDR measurements less than 11 meters, a short pulse should be
+ * used.
+ */
+#define TDR_SHORT_CABLE_LENGTH	11
+
 #define MII_VCT7_PAIR_0_DISTANCE	0x10
 #define MII_VCT7_PAIR_1_DISTANCE	0x11
 #define MII_VCT7_PAIR_2_DISTANCE	0x12
@@ -1828,14 +1833,19 @@ static int marvell_vct5_amplitude_graph(struct phy_device *phydev)
 {
 	struct marvell_priv *priv = phydev->priv;
 	int meters;
+	u16 width;
 	int page;
 	int err;
 	u16 reg;
 
+	if (priv->first <= TDR_SHORT_CABLE_LENGTH)
+		width = MII_VCT5_TX_PULSE_CTRL_PULSE_WIDTH_32nS;
+	else
+		width = MII_VCT5_TX_PULSE_CTRL_PULSE_WIDTH_128nS;
+
 	reg = MII_VCT5_TX_PULSE_CTRL_GT_140m_46_86mV |
 		MII_VCT5_TX_PULSE_CTRL_DONT_WAIT_LINK_DOWN |
-		MII_VCT5_TX_PULSE_CTRL_MAX_AMP |
-		MII_VCT5_TX_PULSE_CTRL_PULSE_WIDTH_32nS;
+		MII_VCT5_TX_PULSE_CTRL_MAX_AMP | width;
 
 	err = phy_write_paged(phydev, MII_MARVELL_VCT5_PAGE,
 			      MII_VCT5_TX_PULSE_CTRL, reg);
@@ -1859,6 +1869,17 @@ static int marvell_vct5_amplitude_graph(struct phy_device *phydev)
 						      priv->pair);
 		if (err)
 			goto restore_page;
+
+		if (meters > TDR_SHORT_CABLE_LENGTH &&
+		    width == MII_VCT5_TX_PULSE_CTRL_PULSE_WIDTH_32nS) {
+			width = MII_VCT5_TX_PULSE_CTRL_PULSE_WIDTH_128nS;
+			reg = MII_VCT5_TX_PULSE_CTRL_GT_140m_46_86mV |
+				MII_VCT5_TX_PULSE_CTRL_DONT_WAIT_LINK_DOWN |
+				MII_VCT5_TX_PULSE_CTRL_MAX_AMP | width;
+			err = __phy_write(phydev, MII_VCT5_TX_PULSE_CTRL, reg);
+			if (err)
+				goto restore_page;
+		}
 	}
 
 restore_page:
-- 
2.26.2


  parent reply	other threads:[~2020-05-24 15:28 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-24 15:27 [PATCH v2 net-next 0/6] Raw PHY TDR data Andrew Lunn
2020-05-24 15:27 ` [PATCH v2 net-next 1/6] net: ethtool: Add attributes for cable test " Andrew Lunn
2020-05-24 15:27 ` [PATCH v2 net-next 2/6] net: ethtool: Add generic parts of cable test TDR Andrew Lunn
2020-05-24 15:27 ` [PATCH v2 net-next 3/6] net: ethtool: Add helpers for cable test TDR data Andrew Lunn
2020-05-24 15:27 ` [PATCH v2 net-next 4/6] net: phy: marvell: Add support for amplitude graph Andrew Lunn
2020-05-24 15:27 ` [PATCH v2 net-next 5/6] net: ethtool: Allow PHY cable test TDR data to configured Andrew Lunn
2020-05-24 20:34   ` Michal Kubecek
2020-05-24 15:27 ` [PATCH v2 net-next 6/6] net : phy: marvell: Speedup TDR data retrieval by only changing page once Andrew Lunn
2020-05-24 16:52   ` Andrew Lunn
2020-05-24 15:27 ` Andrew Lunn [this message]
2020-05-25 18:03 ` [PATCH v2 net-next 0/6] Raw PHY TDR data Chris Healy
  -- strict thread matches above, loose matches on Subject: below --
2020-05-17 19:58 [PATCH net-next 0/7] " Andrew Lunn
2020-05-17 19:58 ` [PATCH net-next 7/7] net: phy: marvell: Configure TDR pulse based on measurement length Andrew Lunn

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