[PATCH 3/3] net: dsa: ksz9477: return negative error codes on PHY access failures

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

The ksz register accessors return a negative error code if the
underlying transport, e.g. i2c, fails. We need to propagate this error
code, instead of reporting incorrect data.

For the case a PHY doesn't exist, reads on a physical bus return 0xFFFF
due to the pull-ups on the MDIO line, so we leave that as is.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/net/ksz9477.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ksz9477.c b/drivers/net/ksz9477.c
index 5c5f4ec8d995..950eb89c09c2 100644
--- a/drivers/net/ksz9477.c
+++ b/drivers/net/ksz9477.c
@@ -29,12 +29,15 @@ static int ksz9477_phy_read16(struct dsa_switch *ds, int addr, int reg)
 {
 	struct device *dev = ds->dev;
 	struct ksz_switch *priv = dev_get_priv(dev);
-	u16 val = 0xffff;
+	int ret;
+	u16 val;
 
 	if (addr >= priv->phy_port_cnt)
-		return val;
+		return 0xffff;
 
-	ksz_pread16(priv, addr, 0x100 + (reg << 1), &val);
+	ret = ksz_pread16(priv, addr, 0x100 + (reg << 1), &val);
+	if (ret)
+		return ret;
 
 	return val;
 }
@@ -52,9 +55,8 @@ static int ksz9477_phy_write16(struct dsa_switch *ds, int addr, int reg,
 	/* No gigabit support.  Do not write to this register. */
 	if (!(priv->features & GBIT_SUPPORT) && reg == MII_CTRL1000)
 		return 0;
-	ksz_pwrite16(priv, addr, 0x100 + (reg << 1), val);
 
-	return 0;
+	return ksz_pwrite16(priv, addr, 0x100 + (reg << 1), val);
 }
 
 static int ksz9477_switch_detect(struct ksz_switch *priv)
-- 
2.39.2