[PATCH net-next] net: stmmac: fix mqprio and cbs combination
Lorenzo Bianconi
lorenzo.bianconi at oss.qualcomm.com
Tue Oct 13 05:24:45 PDT 2026
> > On Oct 13, Daniel Machon wrote:
> > > Hi Lorenzo,
> > >
> > > Just a question:
> > >
> > > > The channel-mode mqprio offload and the CBS offload can currently not be
> > > > enabled at the same time. tc_mqprio_validate_chan_mode() refuses the
> > > > mqprio offload as soon as any TX queue is configured in AVB mode, and
> > > > tc_setup_cbs() refuses to enable CBS while the strict-priority scheduler
> > > > is active. As a result the combination is rejected whichever order the
> > > > two are configured in.
> > > >
> > > > The strict-priority scheduler selected by the channel-mode mqprio
> > > > offload and the per-queue CBS shaper are independent MTL settings and do
> > > > not conflict, so drop the checks and let the combination be offloaded.
> > > > The following configuration, which was previously refused, now works:
> > >
> > > Looks to me like these checks are shared by multiple cores. Are the MTL settings
> > > independent on all of them?
> >
> > Can you please explain what you mean?
> > What I mean with this patch is we can have a given queue (e.g. queue X)
> > configured in MTL_QUEUE_AVB mode and another one (e.g. queue Y) configured
> > in MTL_QUEUE_DCB mode.
>
> Sorry for being vague. I meant the MAC cores. So, dwmac510_tc_ops is being used
> by GMAC, XGMAC, XLGMAC. My question was whether the claim that the commit
> description gives (per-queue CBS shaper are independent MTL settings) apply to
> all of these 3?
Yes, according to my understanding. MTL_QUEUE_AVB and MTL_QUEUE_DCB are
mutually exclusive for a specific queue, but there is no restriction on two
different hw queues (MTL_QUEUE_AVB and MTL_QUEUE_DCB can be mixed).
Regards,
Lorenzo
>
> >
> > Regards,
> > Lorenzo
> >
> > >
> > > >
> > > > $ tc qdisc replace dev eth0 handle 100 parent root mqprio num_tc 4 \
> > > > map 0 0 0 0 0 1 2 3 0 0 0 0 0 0 0 0 \
> > > > queues 1 at 0 1 at 1 1 at 2 1 at 3 mode channel hw 1
> > > > $ tc qdisc replace dev eth0 parent 100:2 handle 102: cbs \
> > > > idleslope 800000 sendslope -1700000 hicredit 494 locredit -1049 offload 0
> > > > $ tc qdisc replace dev eth0 parent 100:3 handle 103: cbs \
> > > > idleslope 400000 sendslope -2100000 hicredit 247 locredit -1296 offload 1
> > > > $ tc qdisc replace dev eth0 parent 100:4 handle 104: cbs \
> > > > idleslope 200000 sendslope -2300000 hicredit 124 locredit -1419 offload 1
> > > >
> > > > Fixes: 47891d501e34 ("net: stmmac: add tc mqprio hw queue priority offload")
> > > > Tested-by: Daniel Thompson <daniel at riscstar.com>
> > > > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi at oss.qualcomm.com>
> > > > ---
> > > > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 8 --------
> > > > drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c | 16 ----------------
> > > > 2 files changed, 24 deletions(-)
> > > >
> > > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > > > index 56d89a696272..51d502930219 100644
> > > > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > > > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > > > @@ -7740,14 +7740,6 @@ int stmmac_reinit_queues(struct net_device *dev, u8 rx_cnt, u8 tx_cnt)
> > > > tx_cnt < priv->xmit_qdisc.num_tx_queues)
> > > > return -EINVAL;
> > > >
> > > > - if (priv->xmit_qdisc.prio_offload) {
> > > > - for (i = priv->plat->tx_queues_to_use; i < tx_cnt; i++) {
> > > > - if (priv->plat->tx_queues_cfg[i].mode_to_use ==
> > > > - MTL_QUEUE_AVB)
> > > > - return -EINVAL;
> > > > - }
> > > > - }
> > > > -
> > > > if (netif_running(dev))
> > > > stmmac_release(dev);
> > > >
> > > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> > > > index ea1f97d6f0bd..175236ba379d 100644
> > > > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> > > > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> > > > @@ -346,9 +346,6 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
> > > > if (!priv->dma_cap.av)
> > > > return -EOPNOTSUPP;
> > > >
> > > > - if (qopt->enable && priv->xmit_qdisc.prio_offload)
> > > > - return -EOPNOTSUPP;
> > > > -
> > > > port_transmit_rate_kbps = qopt->idleslope - qopt->sendslope;
> > > >
> > > > if (qopt->enable) {
> > > > @@ -1340,7 +1337,6 @@ static void tc_mqprio_config_queue_prio(struct stmmac_priv *priv,
> > > > static int tc_mqprio_validate_chan_mode(struct stmmac_priv *priv,
> > > > struct tc_mqprio_qopt_offload *mqprio)
> > > > {
> > > > - struct plat_stmmacenet_data *pdata = priv->plat;
> > > > struct tc_mqprio_qopt *qopt = &mqprio->qopt;
> > > > int i;
> > > >
> > > > @@ -1350,18 +1346,6 @@ static int tc_mqprio_validate_chan_mode(struct stmmac_priv *priv,
> > > > return -EOPNOTSUPP;
> > > > }
> > > >
> > > > - /* Forcing strict priority conflicts with the CBS algorithm
> > > > - * of AVB queues, so reject the offload when any queue is
> > > > - * configured as AVB.
> > > > - */
> > > > - for (i = 0; i < pdata->tx_queues_to_use; i++) {
> > > > - if (pdata->tx_queues_cfg[i].mode_to_use == MTL_QUEUE_AVB) {
> > > > - NL_SET_ERR_MSG_MOD(mqprio->extack,
> > > > - "SP conflicts with AVB queues");
> > > > - return -EOPNOTSUPP;
> > > > - }
> > > > - }
> > > > -
> > > > for (i = 0; i < qopt->num_tc; i++) {
> > > > /* The offload switches the MTL scheduler to strict
> > > > * priority, which only supports a 1:1 TC to TX queue
> > > >
> > > > ---
> > > > base-commit: d0bd617658ddfa5a115e64d1ab687bf155f6331f
> > > > change-id: 20261012-stmmac-mqprio-cbs-combo-341f12749ce2
> > > >
> > > > Best regards,
> > > > --
> > > > Lorenzo Bianconi <lorenzo.bianconi at oss.qualcomm.com>
> > > >
> > >
> > > /Daniel
>
>
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