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From d205110391b7a85af9d45d4e634f1e5595c0a518 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Mon, 26 Nov 2018 19:46:58 +0000
Subject: [PATCH] net: lan78xx: Support auto-downshift to 100Mb/s
Ethernet cables with faulty or missing pairs (specifically pairs C and
D) allow auto-negotiation to 1000Mbs, but do not support the successful
establishment of a link. Add a DT property, "microchip,downshift-after",
to configure the number of auto-negotiation failures after which it
falls back to 100Mbs. Valid values are 2, 3, 4, 5 and 0, where 0 means
never downshift.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
.../bindings/net/microchip,lan78xx.txt | 3 +++
drivers/net/phy/microchip.c | 27 +++++++++++++++++++
include/linux/microchipphy.h | 8 ++++++
3 files changed, 38 insertions(+)
--- a/Documentation/devicetree/bindings/net/microchip,lan78xx.txt
+++ b/Documentation/devicetree/bindings/net/microchip,lan78xx.txt
@@ -14,6 +14,9 @@ Optional properties of the embedded PHY:
- microchip,led-modes: a 0..4 element vector, with each element configuring
the operating mode of an LED. Omitted LEDs are turned off. Allowed values
are defined in "include/dt-bindings/net/microchip-lan78xx.h".
+- microchip,downshift-after: sets the number of failed auto-negotiation
+ attempts after which the link is downgraded from 1000BASE-T. Should be one of
+ 2, 3, 4, 5 or 0, where 0 means never downshift.
Example:
--- a/drivers/net/phy/microchip.c
+++ b/drivers/net/phy/microchip.c
@@ -217,6 +217,7 @@ static int lan88xx_probe(struct phy_devi
struct device *dev = &phydev->mdio.dev;
struct lan88xx_priv *priv;
u32 led_modes[4];
+ u32 downshift_after = 0;
int len;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
@@ -246,6 +247,32 @@ static int lan88xx_probe(struct phy_devi
return -EINVAL;
}
+ if (!of_property_read_u32(dev->of_node,
+ "microchip,downshift-after",
+ &downshift_after)) {
+ u32 mask = LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_MASK;
+ u32 val= LAN78XX_PHY_CTRL3_AUTO_DOWNSHIFT;
+
+ switch (downshift_after) {
+ case 2: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_2;
+ break;
+ case 3: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_3;
+ break;
+ case 4: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_4;
+ break;
+ case 5: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_5;
+ break;
+ case 0: // Disable completely
+ mask = LAN78XX_PHY_CTRL3_AUTO_DOWNSHIFT;
+ val = 0;
+ break;
+ default:
+ return -EINVAL;
+ }
+ (void)phy_modify_paged(phydev, 1, LAN78XX_PHY_CTRL3,
+ mask, val);
+ }
+
/* these values can be used to identify internal PHY */
priv->chip_id = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_ID);
priv->chip_rev = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_REV);
--- a/include/linux/microchipphy.h
+++ b/include/linux/microchipphy.h
@@ -61,6 +61,14 @@
/* Registers specific to the LAN7800/LAN7850 embedded phy */
#define LAN78XX_PHY_LED_MODE_SELECT (0x1D)
+#define LAN78XX_PHY_CTRL3 (0x14)
+#define LAN78XX_PHY_CTRL3_AUTO_DOWNSHIFT (0x0010)
+#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_MASK (0x000c)
+#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_2 (0x0000)
+#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_3 (0x0004)
+#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_4 (0x0008)
+#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_5 (0x000c)
+
/* DSP registers */
#define PHY_ARDENNES_MMD_DEV_3_PHY_CFG (0x806A)
#define PHY_ARDENNES_MMD_DEV_3_PHY_CFG_ZD_DLY_EN_ (0x2000)
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