6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jonas Gorski jonas.gorski@gmail.com
[ Upstream commit 42fb3acf6826c6764ba79feb6e15229b43fd2f9f ]
JMS_MIN_SIZE is the full ethernet frame length, while mtu is just the data payload size. Comparing these two meant that mtus between 1500 and 1518 did not trigger enabling jumbo frames.
So instead compare the set mtu ETH_DATA_LEN, which is equal to JMS_MIN_SIZE - ETH_HLEN - ETH_FCS_LEN;
Also do a check that the requested mtu is actually greater than the minimum length, else we do not need to enable jumbo frames.
In practice this only introduced a very small range of mtus that did not work properly. Newer chips allow 2000 byte large frames by default, and older chips allow 1536 bytes long, which is equivalent to an mtu of 1514. So effectivly only mtus of 1515~1517 were broken.
Fixes: 6ae5834b983a ("net: dsa: b53: add MTU configuration support") Signed-off-by: Jonas Gorski jonas.gorski@gmail.com Reviewed-by: Florian Fainelli florian.fainelli@broadcom.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/dsa/b53/b53_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c index 922e5934de733..862150c54e88e 100644 --- a/drivers/net/dsa/b53/b53_common.c +++ b/drivers/net/dsa/b53/b53_common.c @@ -2224,7 +2224,7 @@ static int b53_change_mtu(struct dsa_switch *ds, int port, int mtu) if (!dsa_is_cpu_port(ds, port)) return 0;
- enable_jumbo = (mtu >= JMS_MIN_SIZE); + enable_jumbo = (mtu > ETH_DATA_LEN); allow_10_100 = (dev->chip_id == BCM583XX_DEVICE_ID);
return b53_set_jumbo(dev, enable_jumbo, allow_10_100);