diff options
Diffstat (limited to 'target/linux/generic/backport-5.15/752-v5.16-net-dsa-qca8k-fix-MTU-calculation.patch')
| -rw-r--r-- | target/linux/generic/backport-5.15/752-v5.16-net-dsa-qca8k-fix-MTU-calculation.patch | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/target/linux/generic/backport-5.15/752-v5.16-net-dsa-qca8k-fix-MTU-calculation.patch b/target/linux/generic/backport-5.15/752-v5.16-net-dsa-qca8k-fix-MTU-calculation.patch new file mode 100644 index 0000000000..7348d93ec4 --- /dev/null +++ b/target/linux/generic/backport-5.15/752-v5.16-net-dsa-qca8k-fix-MTU-calculation.patch @@ -0,0 +1,46 @@ +From 65258b9d8cde45689bdc86ca39b50f01f983733b Mon Sep 17 00:00:00 2001 +From: Robert Marko <robert.marko@sartura.hr> +Date: Fri, 19 Nov 2021 03:03:50 +0100 +Subject: [PATCH] net: dsa: qca8k: fix MTU calculation + +qca8k has a global MTU, so its tracking the MTU per port to make sure +that the largest MTU gets applied. +Since it uses the frame size instead of MTU the driver MTU change function +will then add the size of Ethernet header and checksum on top of MTU. + +The driver currently populates the per port MTU size as Ethernet frame +length + checksum which equals 1518. + +The issue is that then MTU change function will go through all of the +ports, find the largest MTU and apply the Ethernet header + checksum on +top of it again, so for a desired MTU of 1500 you will end up with 1536. + +This is obviously incorrect, so to correct it populate the per port struct +MTU with just the MTU and not include the Ethernet header + checksum size +as those will be added by the MTU change function. + +Fixes: f58d2598cf70 ("net: dsa: qca8k: implement the port MTU callbacks") +Signed-off-by: Robert Marko <robert.marko@sartura.hr> +Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> +Reviewed-by: Vladimir Oltean <olteanv@gmail.com> +Signed-off-by: David S. Miller <davem@davemloft.net> +--- + drivers/net/dsa/qca8k.c | 6 +++++- + 1 file changed, 5 insertions(+), 1 deletion(-) + +--- a/drivers/net/dsa/qca8k.c ++++ b/drivers/net/dsa/qca8k.c +@@ -1256,8 +1256,12 @@ qca8k_setup(struct dsa_switch *ds) + /* Set initial MTU for every port. + * We have only have a general MTU setting. So track + * every port and set the max across all port. ++ * Set per port MTU to 1500 as the MTU change function ++ * will add the overhead and if its set to 1518 then it ++ * will apply the overhead again and we will end up with ++ * MTU of 1536 instead of 1518 + */ +- priv->port_mtu[i] = ETH_FRAME_LEN + ETH_FCS_LEN; ++ priv->port_mtu[i] = ETH_DATA_LEN; + } + + /* Special GLOBAL_FC_THRESH value are needed for ar8327 switch */ |