Re: [RFC net-next 4/5] net: airoha: Add sched ETS offload support

[Lorenzo Bianconi <lorenzo@kernel.org>]

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On Dec 12, Davide Caratti wrote:
> hi Lorenzo,
> 
> On Wed, Dec 11, 2024 at 4:32 PM Lorenzo Bianconi <lorenzo@kernel.org> wrote:
> >
> > Introduce support for ETS qdisc offload available in the Airoha EN7581
> > ethernet controller. Add the capability to configure hw ETS Qdisc for
> > the specified DSA user port via the QDMA block available in the mac chip
> > (QDMA block is connected to the DSA switch cpu port).
> >
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > ---
> >  drivers/net/ethernet/mediatek/airoha_eth.c | 155 ++++++++++++++++++++-
> >  1 file changed, 154 insertions(+), 1 deletion(-)
> >
> [...]
> 
> > +static int airoha_qdma_set_tx_ets_sched(struct airoha_gdm_port *port,
> > +                                       int channel,
> > +                                       struct tc_ets_qopt_offload *opt)
> > +{
> > +       struct tc_ets_qopt_offload_replace_params *p = &opt->replace_params;
> > +       enum tx_sched_mode mode = TC_SCH_SP;
> > +       u16 w[AIROHA_NUM_QOS_QUEUES] = {};
> > +       int i, nstrict = 0;
> > +
> > +       if (p->bands != AIROHA_NUM_QOS_QUEUES)
> > +               return -EINVAL;
> 
> maybe this condition can be relaxed to '<'  if priomap is parsed ? (see below)

ack, I guess we can relax a bit this condition.

> 
> > +
> > +       for (i = 0; i < p->bands; i++) {
> > +               if (!p->quanta[i])
> > +                       nstrict++;
> > +       }
> > +
> > +       /* this configuration is not supported by the hw */
> > +       if (nstrict == AIROHA_NUM_QOS_QUEUES - 1)
> > +               return -EINVAL;
> > +
> > +       for (i = 0; i < p->bands - nstrict; i++)
> > +               w[i] = p->weights[nstrict + i];
> > +
> > +       if (!nstrict)
> > +               mode = TC_SCH_WRR8;
> > +       else if (nstrict < AIROHA_NUM_QOS_QUEUES - 1)
> > +               mode = nstrict + 1;
> > +
> > +       return airoha_qdma_set_chan_tx_sched(port, channel, mode, w,
> > +                                            ARRAY_SIZE(w));
> 
> it seems that SP queues have a fixed, non-programmable priority in
> hardware (e.g., queue 7 is served prior to queue 6) If this is the
> case, you probably have to ensure that 'priomap' maps correctly
> skb->priority to one of the SP queues, like done in [1].

ack, I will take a look.

Regards,
Lorenzo

> 
> thanks,
> -- 
> davide
> 
> [1] https://elixir.bootlin.com/linux/v6.12.4/source/drivers/net/ethernet/microchip/lan966x/lan966x_ets.c#L41
> 

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