net: phy: broadcom: optionally enable link-down powersave based on DT

It's really a function of the board whether or not to use this feature
as it may require MAC compatibility as well as interop testing.

Signed-off-by: Jonathan Bell <[email protected]>

Author: P33M

drivers/net/phy/broadcom.c

@@ -463,6 +463,9 @@ static int bcm54xx_config_init(struct phy_device *phydev)
 	    (phydev->dev_flags & PHY_BRCM_CLEAR_RGMII_MODE))
 		bcm_phy_write_shadow(phydev, BCM54XX_SHD_RGMII_MODE, 0);
 
+	if (of_property_read_bool(np, "brcm,powerdown-enable"))
+		phydev->dev_flags |= PHY_BRCM_AUTO_PWRDWN_ENABLE;
+
 	bcm54xx_adjust_rxrefclk(phydev);
 
 	switch (BRCM_PHY_MODEL(phydev)) {