1 From d205110391b7a85af9d45d4e634f1e5595c0a518 Mon Sep 17 00:00:00 2001
2 From: Phil Elwell <phil@raspberrypi.org>
3 Date: Mon, 26 Nov 2018 19:46:58 +0000
4 Subject: [PATCH] net: lan78xx: Support auto-downshift to 100Mb/s
6 Ethernet cables with faulty or missing pairs (specifically pairs C and
7 D) allow auto-negotiation to 1000Mbs, but do not support the successful
8 establishment of a link. Add a DT property, "microchip,downshift-after",
9 to configure the number of auto-negotiation failures after which it
10 falls back to 100Mbs. Valid values are 2, 3, 4, 5 and 0, where 0 means
13 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
15 .../bindings/net/microchip,lan78xx.txt | 3 +++
16 drivers/net/phy/microchip.c | 27 +++++++++++++++++++
17 include/linux/microchipphy.h | 8 ++++++
18 3 files changed, 38 insertions(+)
20 --- a/Documentation/devicetree/bindings/net/microchip,lan78xx.txt
21 +++ b/Documentation/devicetree/bindings/net/microchip,lan78xx.txt
22 @@ -14,6 +14,9 @@ Optional properties of the embedded PHY:
23 - microchip,led-modes: a 0..4 element vector, with each element configuring
24 the operating mode of an LED. Omitted LEDs are turned off. Allowed values
25 are defined in "include/dt-bindings/net/microchip-lan78xx.h".
26 +- microchip,downshift-after: sets the number of failed auto-negotiation
27 + attempts after which the link is downgraded from 1000BASE-T. Should be one of
28 + 2, 3, 4, 5 or 0, where 0 means never downshift.
32 --- a/drivers/net/phy/microchip.c
33 +++ b/drivers/net/phy/microchip.c
34 @@ -217,6 +217,7 @@ static int lan88xx_probe(struct phy_devi
35 struct device *dev = &phydev->mdio.dev;
36 struct lan88xx_priv *priv;
38 + u32 downshift_after = 0;
41 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
42 @@ -246,6 +247,32 @@ static int lan88xx_probe(struct phy_devi
46 + if (!of_property_read_u32(dev->of_node,
47 + "microchip,downshift-after",
48 + &downshift_after)) {
49 + u32 mask = LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_MASK;
50 + u32 val= LAN78XX_PHY_CTRL3_AUTO_DOWNSHIFT;
52 + switch (downshift_after) {
53 + case 2: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_2;
55 + case 3: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_3;
57 + case 4: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_4;
59 + case 5: val |= LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_5;
61 + case 0: // Disable completely
62 + mask = LAN78XX_PHY_CTRL3_AUTO_DOWNSHIFT;
68 + (void)phy_modify_paged(phydev, 1, LAN78XX_PHY_CTRL3,
72 /* these values can be used to identify internal PHY */
73 priv->chip_id = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_ID);
74 priv->chip_rev = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_REV);
75 --- a/include/linux/microchipphy.h
76 +++ b/include/linux/microchipphy.h
78 /* Registers specific to the LAN7800/LAN7850 embedded phy */
79 #define LAN78XX_PHY_LED_MODE_SELECT (0x1D)
81 +#define LAN78XX_PHY_CTRL3 (0x14)
82 +#define LAN78XX_PHY_CTRL3_AUTO_DOWNSHIFT (0x0010)
83 +#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_MASK (0x000c)
84 +#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_2 (0x0000)
85 +#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_3 (0x0004)
86 +#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_4 (0x0008)
87 +#define LAN78XX_PHY_CTRL3_DOWNSHIFT_CTRL_5 (0x000c)
90 #define PHY_ARDENNES_MMD_DEV_3_PHY_CFG (0x806A)
91 #define PHY_ARDENNES_MMD_DEV_3_PHY_CFG_ZD_DLY_EN_ (0x2000)