[PATCH v2 2/2] sungem: validate BCM5411 PHY register reads

[Joel <joelcrouch@gmail.com>]

Check for -EIO and 0xffff during initialization to prevent silent failures. Add error logging to gem_init_phy to report failures.
---
 drivers/net/ethernet/sun/sungem.c | 8 ++++++--
 drivers/net/sungem_phy.c          | 7 ++++++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/sun/sungem.c b/drivers/net/ethernet/sun/sungem.c
index 8e69d917d..525aba527 100644
--- a/drivers/net/ethernet/sun/sungem.c
+++ b/drivers/net/ethernet/sun/sungem.c
@@ -1707,8 +1707,12 @@ static void gem_init_phy(struct gem *gp)
 		sungem_phy_probe(&gp->phy_mii, gp->mii_phy_addr);
 
 		/* Init PHY */
-		if (gp->phy_mii.def && gp->phy_mii.def->ops->init)
-			gp->phy_mii.def->ops->init(&gp->phy_mii);
+		if (gp->phy_mii.def && gp->phy_mii.def->ops->init) {
+			int err = gp->phy_mii.def->ops->init(&gp->phy_mii);
+
+			if (err)
+				netdev_err(gp->dev, "PHY init failed: %d\n", err);
+		}
 	} else {
 		gem_pcs_reset(gp);
 		gem_pcs_reinit_adv(gp);
diff --git a/drivers/net/sungem_phy.c b/drivers/net/sungem_phy.c
index 44cbe1938..ec8800c93 100644
--- a/drivers/net/sungem_phy.c
+++ b/drivers/net/sungem_phy.c
@@ -296,7 +296,12 @@ static int bcm5411_init(struct mii_phy *phy)
 	sungem_phy_write(phy, MII_BMCR, BMCR_RESET);
 	sungem_phy_write(phy, MII_BMCR, 0x1340);
 
-	data = sungem_phy_read(phy, MII_BCM5400_GB_CONTROL);
+	val = sungem_phy_read(phy, MII_BCM5400_GB_CONTROL);
+
+	if (val < 0 || val == 0xffff)
+		return -EIO;
+
+	data = (u16)val;
 	data |= MII_BCM5400_GB_CONTROL_FULLDUPLEXCAP;
 	sungem_phy_write(phy, MII_BCM5400_GB_CONTROL, data);
 
-- 
2.43.0