From: Vladimir Oltean vladimir.oltean@nxp.com
[ Upstream commit 7e9517375a14f44ee830ca1c3278076dd65fcc8f ]
There are 3 classes of switch families that the driver is aware of, as far as mv88e6xxx_change_mtu() is concerned:
- MTU configuration is available per port. Here, the chip->info->ops->port_set_jumbo_size() method will be present.
- MTU configuration is global to the switch. Here, the chip->info->ops->set_max_frame_size() method will be present.
- We don't know how to change the MTU. Here, none of the above methods will be present.
Switch families MV88E6165, MV88E6191, MV88E6220, MV88E6250 and MV88E6290 fall in category 3.
The blamed commit has adjusted the MTU for all 3 categories by EDSA_HLEN (8 bytes), resulting in a new maximum MTU of 1492 being reported by the driver for these switches.
I don't have the hardware to test, but I do have a MV88E6390 switch on which I can simulate this by commenting out its .port_set_jumbo_size definition from mv88e6390_ops. The result is this set of messages at probe time:
mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 1 mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 2 mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 3 mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 4 mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 5 mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 6 mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 7 mv88e6085 d0032004.mdio-mii:10: nonfatal error -34 setting MTU to 1500 on port 8
It is highly implausible that there exist Ethernet switches which don't support the standard MTU of 1500 octets, and this is what the DSA framework says as well - the error comes from dsa_slave_create() -> dsa_slave_change_mtu(slave_dev, ETH_DATA_LEN).
But the error messages are alarming, and it would be good to suppress them.
As a consequence of this unlikeliness, we reimplement mv88e6xxx_get_max_mtu() and mv88e6xxx_change_mtu() on switches from the 3rd category as follows: the maximum supported MTU is 1500, and any request to set the MTU to a value larger than that fails in dev_validate_mtu().
Fixes: b9c587fed61c ("dsa: mv88e6xxx: Include tagger overhead when setting MTU for DSA and CPU ports") Signed-off-by: Vladimir Oltean vladimir.oltean@nxp.com Reviewed-by: Simon Horman simon.horman@corigine.com Reviewed-by: Florian Fainelli f.fainelli@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/dsa/mv88e6xxx/chip.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index 242b8b325504a..89829e0ca8e8f 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c @@ -3549,7 +3549,7 @@ static int mv88e6xxx_get_max_mtu(struct dsa_switch *ds, int port) return 10240 - VLAN_ETH_HLEN - EDSA_HLEN - ETH_FCS_LEN; else if (chip->info->ops->set_max_frame_size) return 1632 - VLAN_ETH_HLEN - EDSA_HLEN - ETH_FCS_LEN; - return 1522 - VLAN_ETH_HLEN - EDSA_HLEN - ETH_FCS_LEN; + return ETH_DATA_LEN; }
static int mv88e6xxx_change_mtu(struct dsa_switch *ds, int port, int new_mtu) @@ -3557,6 +3557,17 @@ static int mv88e6xxx_change_mtu(struct dsa_switch *ds, int port, int new_mtu) struct mv88e6xxx_chip *chip = ds->priv; int ret = 0;
+ /* For families where we don't know how to alter the MTU, + * just accept any value up to ETH_DATA_LEN + */ + if (!chip->info->ops->port_set_jumbo_size && + !chip->info->ops->set_max_frame_size) { + if (new_mtu > ETH_DATA_LEN) + return -EINVAL; + + return 0; + } + if (dsa_is_dsa_port(ds, port) || dsa_is_cpu_port(ds, port)) new_mtu += EDSA_HLEN;
@@ -3565,9 +3576,6 @@ static int mv88e6xxx_change_mtu(struct dsa_switch *ds, int port, int new_mtu) ret = chip->info->ops->port_set_jumbo_size(chip, port, new_mtu); else if (chip->info->ops->set_max_frame_size) ret = chip->info->ops->set_max_frame_size(chip, new_mtu); - else - if (new_mtu > 1522) - ret = -EINVAL; mv88e6xxx_reg_unlock(chip);
return ret;