Re: [PATCH net-next v1 2/8] net: ieee8021q: add pcp_to_tt()

[Linus Walleij]

On Fri, Oct 2, 2026 at 1:58 PM Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote:

> Add a helper that maps an IEEE 802.1Q Priority Code Point (PCP) to the
> corresponding 802.1Q traffic type, complementing the existing
> ietf_dscp_to_ieee8021q_tt().
>
> It is very nearly an identity map, except that PCP 0 (Best Effort) and
> PCP 1 (Background) are swapped: per 802.1Q-2022 (Annex I, Table I-2)
> Background is a lower priority than Best Effort even though it carries
> the higher PCP value. PCP 2..7 map straight through to the matching
> traffic type, and values above 7 are rejected with -EINVAL. This decodes
> the 8P0D encoding (Table I-7), where every PCP value is a priority and
> none carries drop eligibility.
>
> Drivers that classify ingress traffic by PCP need this to map into a
> priority-ordered internal space without misordering Best Effort and
> Background. The first consumer, the realtek rtl8365mb DSA driver, lands
> later in this series.
>
> Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>

This looks very generally helpful.
Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>

Yours,
Linus Walleij