[PATCH v2] net/phy/vitesse: Configure RGMII skew on VSC8601, if needed
From: Alexandru Gagniuc <hidden>
Date: 2016-11-16 10:36:27
Also in:
lkml
Subsystem:
ethernet phy library, networking drivers, the rest · Maintainers:
Andrew Lunn, Heiner Kallweit, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <redacted> --- Changes since v1: * Added comment detailing applicability to different RGMII interfaces. 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 2e37eb3..24b4a09 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,
--
2.7.4