From db8668a1951954156c039b9f8fe2881d428a522c Mon Sep 17 00:00:00 2001
From: Andrew Lunn <andrew@lunn.ch>
Date: Wed, 27 May 2020 00:21:43 +0200
Subject: [PATCH] net: phy: marvell: Configure TDR pulse based on measurement
length
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
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 e9deedea5f19a..2c04e3b2b285f 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
@@ -1835,14 +1840,19 @@ static int marvell_vct5_amplitude_graph(struct phy_device *phydev)
{
struct marvell_priv *priv = phydev->priv;
int distance;
+ 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);
@@ -1866,6 +1876,17 @@ static int marvell_vct5_amplitude_graph(struct phy_device *phydev)
priv->pair);
if (err)
goto restore_page;
+
+ if (distance > 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:
--
2.30.2