net: fec: account for VLAN header in frame length calculations

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The MAX_FL (maximum frame length) and related calculations used ETH_HLEN,
which does not account for the 4-byte VLAN tag in tagged frames. This
caused the hardware to reject valid VLAN frames as oversized, resulting
in RX errors and dropped packets.

Use VLAN_ETH_HLEN instead of ETH_HLEN in the MAX_FL register setup,
cut-through mode threshold, buffer allocation, and max_mtu calculation.

Cc: stable@kernel.org # v6.18+
Fixes: 62b5bb7be7 ("net: fec: update MAX_FL based on the current MTU")
Fixes: d466c16026 ("net: fec: enable the Jumbo frame support for i.MX8QM")
Fixes: 59e9bf037d ("net: fec: add change_mtu to support dynamic buffer allocation")
Fixes: ec2a1681ed ("net: fec: use a member variable for maximum buffer size")
Signed-off-by: Clemens Gruber <mail@clemensgruber.at>
Reviewed-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20260121083751.66997-1-mail@clemensgruber.at
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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Clemens Gruber 2026-01-21 09:37:51 +01:00 • committed by Paolo Abeni

parent cc4816bdb0

commit ca1bb3fedf

1 changed files with 7 additions and 6 deletions

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drivers/net/ethernet/freescale/fec_main.c

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