[PATCH v2 1/7] net: phy: genphy_loopback: add link speed configuration

[Oleksij Rempel]

In case of loopback, in most cases we need to disable autoneg support
and force some speed configuration. Otherwise, depending on currently
active auto negotiated link speed, the loopback may or may not work.

This patch was tested with following PHYs: TJA1102, KSZ8081, KSZ9031,
AT8035, AR9331.

Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
 drivers/net/phy/phy.c        |  3 ++-
 drivers/net/phy/phy_device.c | 21 +++++++++++++++++++--
 include/linux/phy.h          |  1 +
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index fc2e7cb5b2e5..1f0512e39c65 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -701,7 +701,7 @@ int phy_start_cable_test_tdr(struct phy_device *phydev,
 }
 EXPORT_SYMBOL(phy_start_cable_test_tdr);
 
-static int phy_config_aneg(struct phy_device *phydev)
+int phy_config_aneg(struct phy_device *phydev)
 {
 	if (phydev->drv->config_aneg)
 		return phydev->drv->config_aneg(phydev);
@@ -714,6 +714,7 @@ static int phy_config_aneg(struct phy_device *phydev)
 
 	return genphy_config_aneg(phydev);
 }
+EXPORT_SYMBOL(phy_config_aneg);
 
 /**
  * phy_check_link_status - check link status and set state accordingly
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 73d29fd5e03d..f484f191d2ff 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2562,8 +2562,25 @@ EXPORT_SYMBOL(genphy_resume);
 
 int genphy_loopback(struct phy_device *phydev, bool enable)
 {
-	return phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK,
-			  enable ? BMCR_LOOPBACK : 0);
+	if (enable) {
+		u16 ctl = BMCR_LOOPBACK;
+
+		if (phydev->speed == SPEED_1000)
+			ctl |= BMCR_SPEED1000;
+		else if (phydev->speed == SPEED_100)
+			ctl |= BMCR_SPEED100;
+
+		if (phydev->duplex == DUPLEX_FULL)
+			ctl |= BMCR_FULLDPLX;
+
+		phy_modify(phydev, MII_BMCR, ~0, ctl);
+	} else {
+		phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK, 0);
+
+		phy_config_aneg(phydev);
+	}
+
+	return 0;
 }
 EXPORT_SYMBOL(genphy_loopback);
 
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 98fb441dd72e..98e351bb0964 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1410,6 +1410,7 @@ void phy_disconnect(struct phy_device *phydev);
 void phy_detach(struct phy_device *phydev);
 void phy_start(struct phy_device *phydev);
 void phy_stop(struct phy_device *phydev);
+int phy_config_aneg(struct phy_device *phydev);
 int phy_start_aneg(struct phy_device *phydev);
 int phy_aneg_done(struct phy_device *phydev);
 int phy_speed_down(struct phy_device *phydev, bool sync);
-- 
2.29.2