From 955e16026d08a601d02b961d13b6db9d6c13c8c9 Mon Sep 17 00:00:00 2001 From: Alex Date: Wed, 16 Nov 2016 01:02:33 -0800 Subject: [PATCH] net/phy/vitesse: Configure RGMII skew on VSC8601, if needed With RGMII, we need a 1.5 to 2ns skew between clock and data lines. The VSC8601 can handle this internally. While the VSC8601 can set more fine-grained delays, the standard skew settings work out of the box. The same heuristic is used to determine when this skew should be enabled as in vsc824x_config_init(). Tested on custom board with AM3352 SOC and VSC801 PHY. Signed-off-by: Alexandru Gagniuc Signed-off-by: David S. Miller --- drivers/net/phy/vitesse.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/drivers/net/phy/vitesse.c b/drivers/net/phy/vitesse.c index 2e37eb337d48..24b4a09468dd 100644 --- a/drivers/net/phy/vitesse.c +++ b/drivers/net/phy/vitesse.c @@ -62,6 +62,10 @@ /* Vitesse Extended Page Access Register */ #define MII_VSC82X4_EXT_PAGE_ACCESS 0x1f +/* Vitesse VSC8601 Extended PHY Control Register 1 */ +#define MII_VSC8601_EPHY_CTL 0x17 +#define MII_VSC8601_EPHY_CTL_RGMII_SKEW (1 << 8) + #define PHY_ID_VSC8234 0x000fc620 #define PHY_ID_VSC8244 0x000fc6c0 #define PHY_ID_VSC8514 0x00070670 @@ -111,6 +115,34 @@ static int vsc824x_config_init(struct phy_device *phydev) return err; } +/* This adds a skew for both TX and RX clocks, so the skew should only be + * applied to "rgmii-id" interfaces. It may not work as expected + * on "rgmii-txid", "rgmii-rxid" or "rgmii" interfaces. */ +static int vsc8601_add_skew(struct phy_device *phydev) +{ + int ret; + + ret = phy_read(phydev, MII_VSC8601_EPHY_CTL); + if (ret < 0) + return ret; + + ret |= MII_VSC8601_EPHY_CTL_RGMII_SKEW; + return phy_write(phydev, MII_VSC8601_EPHY_CTL, ret); +} + +static int vsc8601_config_init(struct phy_device *phydev) +{ + int ret = 0; + + if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) + ret = vsc8601_add_skew(phydev); + + if (ret < 0) + return ret; + + return genphy_config_init(phydev); +} + static int vsc824x_ack_interrupt(struct phy_device *phydev) { int err = 0; @@ -275,7 +307,7 @@ static struct phy_driver vsc82xx_driver[] = { .phy_id_mask = 0x000ffff0, .features = PHY_GBIT_FEATURES, .flags = PHY_HAS_INTERRUPT, - .config_init = &genphy_config_init, + .config_init = &vsc8601_config_init, .config_aneg = &genphy_config_aneg, .read_status = &genphy_read_status, .ack_interrupt = &vsc824x_ack_interrupt, -- 2.20.1