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net: lan78xx: Support auto-downshift to 100Mb/s

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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>
This commit is contained in:
Phil Elwell
2018-11-26 19:46:58 +00:00
committed by Dom Cobley
parent 43f21beb94
commit 222ef7050b
3 changed files with 38 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/devicetree/bindings/net/microchip,lan78xx.txt
View File

@@ -14,6 +14,9 @@ Optional properties of the embedded PHY:
- microchip,led-modes: a 0..4 element vector, with each element configuring - 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 the operating mode of an LED. Omitted LEDs are turned off. Allowed values
are defined in "include/dt-bindings/net/microchip-lan78xx.h". 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: Example:

27
drivers/net/phy/microchip.c
View File

@@ -233,6 +233,7 @@ static int lan88xx_probe(struct phy_device *phydev)
struct device *dev = &phydev->mdio.dev; struct device *dev = &phydev->mdio.dev;
struct lan88xx_priv *priv; struct lan88xx_priv *priv;
u32 led_modes[4]; u32 led_modes[4];
u32 downshift_after = 0;
int len; int len;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
@@ -262,6 +263,32 @@ static int lan88xx_probe(struct phy_device *phydev)
return -EINVAL; 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 */ /* these values can be used to identify internal PHY */
priv->chip_id = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_ID); priv->chip_id = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_ID);
priv->chip_rev = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_REV); priv->chip_rev = phy_read_mmd(phydev, 3, LAN88XX_MMD3_CHIP_REV);

8
include/linux/microchipphy.h
View File

@@ -61,6 +61,14 @@
/* Registers specific to the LAN7800/LAN7850 embedded phy */ /* Registers specific to the LAN7800/LAN7850 embedded phy */
#define LAN78XX_PHY_LED_MODE_SELECT (0x1D) #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 */ /* DSP registers */
#define PHY_ARDENNES_MMD_DEV_3_PHY_CFG (0x806A) #define PHY_ARDENNES_MMD_DEV_3_PHY_CFG (0x806A)
#define PHY_ARDENNES_MMD_DEV_3_PHY_CFG_ZD_DLY_EN_ (0x2000) #define PHY_ARDENNES_MMD_DEV_3_PHY_CFG_ZD_DLY_EN_ (0x2000)