netdev - Re: [PATCH v2] net: fec: account for VLAN header in frame length calculations

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Message-ID: <578b5c27-0db5-4185-ad3b-cb35bf864d18@redhat.com>
Date: Thu, 22 Jan 2026 13:23:53 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Clemens Gruber <mail@...mensgruber.at>, wei.fang@....com,
 andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org
Cc: shenwei.wang@....com, xiaoning.wang@....com, imx@...ts.linux.dev,
 netdev@...r.kernel.org, stable@...nel.org
Subject: Re: [PATCH v2] net: fec: account for VLAN header in frame length
 calculations

On 1/21/26 9:37 AM, Clemens Gruber wrote:
> 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@...nel.org # v6.18+
> Fixes: 62b5bb7be7bc ("net: fec: update MAX_FL based on the current MTU")
> Fixes: d466c16026e9 ("net: fec: enable the Jumbo frame support for i.MX8QM")
> Fixes: 59e9bf037d75 ("net: fec: add change_mtu to support dynamic buffer allocation")
> Fixes: ec2a1681ed4f ("net: fec: use a member variable for maximum buffer size")
> Signed-off-by: Clemens Gruber <mail@...mensgruber.at>

A couple of things to remember for future submissions: you should
include the target tree into the subj prefix ('net' in this case) and
you should avoid sending you revision in reply to older ones as it may
foul patchwork.

No repost needed, the patch looks good, I'm applying it.

Thanks,

Paolo