[PATCH net 1/3] net: phy: bcm7xxx: workaround MDIO management controller initial read
From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2015-06-26 17:40:40
Subsystem:
broadcom ethernet phy drivers, ethernet phy library, networking drivers, the rest · Maintainers:
Florian Fainelli, Andrew Lunn, Heiner Kallweit, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The initial MDIO read or write towards the BCM7xxx integrated PHY may fail, workaround this by inserting a dummy MII_BMSR read to force the MDIO management controller to see at least one valid transaction and get out of stuck state out of reset. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> --- drivers/net/phy/bcm7xxx.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/net/phy/bcm7xxx.c b/drivers/net/phy/bcm7xxx.c
index 4dea85bfc545..6b701b3ded74 100644
--- a/drivers/net/phy/bcm7xxx.c
+++ b/drivers/net/phy/bcm7xxx.c@@ -246,6 +246,13 @@ static int bcm7xxx_28nm_config_init(struct phy_device *phydev) pr_info_once("%s: %s PHY revision: 0x%02x, patch: %d\n", dev_name(&phydev->dev), phydev->drv->name, rev, patch); + /* Dummy read to a register to workaround an issue upon reset where the + * internal inverter may not allow the first MDIO transaction to pass + * the MDIO management controller and make us return 0xffff for such + * reads. + */ + phy_read(phydev, MII_BMSR); + switch (rev) { case 0xb0: ret = bcm7xxx_28nm_b0_afe_config_init(phydev);
--
2.1.0