Re: [PATCH net-next v2 09/10] net: dsa: realtek: rtl8365mb: offload DCB apptrust

[Luiz Angelo Daros de Luca]

> > Wire up port_get_apptrust and port_set_apptrust. The admin can then
> > choose through dcbnl apptrust which ingress classification a port trusts
> > for its priority: 802.1p (PCP), DSCP or both. A port that trusts nothing
> > keeps the port default priority.
> >
> > In the driver's model of the hardware, the trusted priority-decision
> > table is switch-wide, so all ports that trust something must trust the
> > same selectors. While another port trusts a set of selectors, a request
> > to trust a different set is refused with -EBUSY.
> >
> > When both are trusted, DSCP must come first. When PCP is trusted, the
> > switch classifies an untagged frame by the PCP given to untagged
> > frames. A PCP source ranked above DSCP would then hide DSCP from
> > untagged IP frames. Refuse the order pcp dscp and any unknown selector
> > with -EOPNOTSUPP.
> >
> > Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
> > ---
> > Changes in v2:
> > - move selector and precedence validation into rtl83xx-qos.c behind new
> >   qos_get/set_apptrust callbacks; weights and -EBUSY stay here (Linus)
> > - use one-hot decision weights; in the driver's model, the v1 linear
> >   weights could tie PCP with DSCP (Linus)
> > - define the apptrust slot order once (enum rtl83xx_apptrust_slot) for
> >   the shared selector table and the backend source table
> > - write the PCP and DSCP weights with one register update, so a failed
> >   write cannot leave the trusted table half programmed (sashiko)
> > - check that all apptrust sources share the one register that is updated
> > - rank DSCP above PCP and refuse pcp dscp with -EOPNOTSUPP, because
> >   with PCP first, untagged IP frames never reach DSCP

Reviewed-by: Luiz Angelo Daros de Luca <luizluca@xxxxxxxxx>