[PATCH net v1 1/1] net: dsa: microchip: don't try do read Gbit registers on non Gbit chips

[Oleksij Rempel]

Do not try to read not existing or wrong register on chips without
GBIT_SUPPORT.

Fixes: c2e866911e25 ("net: dsa: microchip: break KSZ9477 DSA driver into two files")
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
 drivers/net/dsa/microchip/ksz9477.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
index c73bb6d383ad..f6bbd9646c85 100644
--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -316,7 +316,13 @@ void ksz9477_r_phy(struct ksz_device *dev, u16 addr, u16 reg, u16 *data)
 			break;
 		}
 	} else {
-		ksz_pread16(dev, addr, 0x100 + (reg << 1), &val);
+		/* No gigabit support.  Do not read wrong registers. */
+		if (!(dev->features & GBIT_SUPPORT) &&
+		    (reg == MII_CTRL1000 || reg == MII_ESTATUS ||
+		     reg == MII_STAT1000))
+			val = 0;
+		else
+			ksz_pread16(dev, addr, 0x100 + (reg << 1), &val);
 	}
 
 	*data = val;
-- 
2.30.2