From a3c59bad71de2b3c09a25fd6ce5e3632c33c4bba Mon Sep 17 00:00:00 2001 From: Phil Elwell 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 --- drivers/net/phy/microchip.c | 32 ++++++++++++++++++++++++++++++++ include/linux/microchipphy.h | 8 ++++++++ 2 files changed, 40 insertions(+) --- a/drivers/net/phy/microchip.c +++ b/drivers/net/phy/microchip.c @@ -228,6 +228,7 @@ 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); @@ -257,6 +258,37 @@ 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 @@ -73,6 +73,14 @@ /* 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)