From: Codrin Ciubotariu <codrin.ciubotariu@xxxxxxxxxxxxx> [ Upstream commit af199a1a9cb02ec0194804bd46c174b6db262075 ] The number of ports is incorrectly set to the maximum available for a DSA switch. Even if the extra ports are not used, this causes some functions to be called later, like port_disable() and port_stp_state_set(). If the driver doesn't check the port index, it will end up modifying unknown registers. Fixes: b987e98e50ab ("dsa: add DSA switch driver for Microchip KSZ9477") Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@xxxxxxxxxxxxx> Reviewed-by: Andrew Lunn <andrew@xxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/dsa/microchip/ksz8795.c | 3 +++ drivers/net/dsa/microchip/ksz9477.c | 3 +++ 2 files changed, 6 insertions(+) --- a/drivers/net/dsa/microchip/ksz8795.c +++ b/drivers/net/dsa/microchip/ksz8795.c @@ -1271,6 +1271,9 @@ static int ksz8795_switch_init(struct ks /* set the real number of ports */ dev->ds->num_ports = dev->port_cnt; + /* set the real number of ports */ + dev->ds->num_ports = dev->port_cnt; + return 0; } --- a/drivers/net/dsa/microchip/ksz9477.c +++ b/drivers/net/dsa/microchip/ksz9477.c @@ -516,6 +516,9 @@ static int ksz9477_port_vlan_filtering(s PORT_VLAN_LOOKUP_VID_0, false); } + /* set the real number of ports */ + dev->ds->num_ports = dev->port_cnt; + return 0; }