net: dsa: bcm_sf2: disable RGMII interface(s) when link is down

When the link is down, disable the RGMII interface to conserve as much
power as possible. We re-enable the RGMII interface whenever the link is
detected.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c
index d9b7da5..58b8fef 100644
--- a/drivers/net/dsa/bcm_sf2.c
+++ b/drivers/net/dsa/bcm_sf2.c
@@ -506,6 +506,15 @@
 		port_mode = EXT_REVMII;
 		break;
 	default:
+		/* All other PHYs: internal and MoCA */
+		goto force_link;
+	}
+
+	/* If the link is down, just disable the interface to conserve power */
+	if (!phydev->link) {
+		reg = reg_readl(priv, REG_RGMII_CNTRL_P(port));
+		reg &= ~RGMII_MODE_EN;
+		reg_writel(priv, reg, REG_RGMII_CNTRL_P(port));
 		goto force_link;
 	}