Re: [PATCH] net: dsa: tag_rtl4_a: Support also egress tags

On Wed, Feb 17, 2021 at 01:37:21PM +0800, DENG Qingfang wrote:

On Wed, Feb 17, 2021 at 11:29 AM Andrew Lunn [off-list ref] wrote:

quoted

quoted

+     /* Pad out to at least 60 bytes */
+     if (unlikely(eth_skb_pad(skb)))
+             return NULL;

The core will do the padding for you. Turn on .tail_tag in
dsa_device_ops.

Please don't. .tail_tag does far more than just padding.

Qingfang is right, this is an EtherType tagging protocol not a tail tagger.

Note that there was an interesting discussion with Florian and Kuba
around the Broadcom switches that require padding for short frames too:
https://patchwork.kernel.org/project/netdevbpf/patch/20201101191620.589272-10-vladimir.oltean@nxp.com/