* Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination
2026-10-12 21:14 [PATCH net-next] net: stmmac: fix mqprio and cbs combination Lorenzo Bianconi
@ 2026-10-13 9:51 ` Daniel Thompson
2026-10-13 9:58 ` Maxime Chevallier
` (2 subsequent siblings)
3 siblings, 0 replies; 8+ messages in thread
From: Daniel Thompson @ 2026-10-13 9:51 UTC (permalink / raw)
To: Lorenzo Bianconi
Cc: Maxime Chevallier, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin, Alexandre Torgue,
Davide Caratti, netdev, linux-arm-kernel
On Mon, Oct 12, 2026 at 11:14:06PM +0200, Lorenzo Bianconi wrote:
> 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:
>
> $ 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@0 1@1 1@2 1@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@riscstar.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
Also FWIW:
Reviewed-by: Daniel Thompson <daniel@riscstar.com>
Daniel.
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination
2026-10-12 21:14 [PATCH net-next] net: stmmac: fix mqprio and cbs combination Lorenzo Bianconi
2026-10-13 9:51 ` Daniel Thompson
@ 2026-10-13 9:58 ` Maxime Chevallier
2026-10-13 10:10 ` Daniel Machon
2026-10-13 21:15 ` netdev-bot+sashiko
3 siblings, 0 replies; 8+ messages in thread
From: Maxime Chevallier @ 2026-10-13 9:58 UTC (permalink / raw)
To: Lorenzo Bianconi, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin, Alexandre Torgue,
Davide Caratti
Cc: netdev, linux-arm-kernel, Daniel Thompson
Hi,
On 10/12/26 23:14, Lorenzo Bianconi wrote:
> 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:
>
> $ 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@0 1@1 1@2 1@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@riscstar.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Thank you Lorenzo,
Maxime
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination
2026-10-12 21:14 [PATCH net-next] net: stmmac: fix mqprio and cbs combination Lorenzo Bianconi
2026-10-13 9:51 ` Daniel Thompson
2026-10-13 9:58 ` Maxime Chevallier
@ 2026-10-13 10:10 ` Daniel Machon
2026-10-13 10:21 ` Lorenzo Bianconi
2026-10-13 21:15 ` netdev-bot+sashiko
3 siblings, 1 reply; 8+ messages in thread
From: Daniel Machon @ 2026-10-13 10:10 UTC (permalink / raw)
To: Lorenzo Bianconi
Cc: Maxime Chevallier, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin, Alexandre Torgue,
Davide Caratti, netdev, linux-arm-kernel, Daniel Thompson
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?
>
> $ 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@0 1@1 1@2 1@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@riscstar.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@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@oss.qualcomm.com>
>
/Daniel
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination
2026-10-13 10:10 ` Daniel Machon
@ 2026-10-13 10:21 ` Lorenzo Bianconi
2026-10-13 10:43 ` Daniel Machon
0 siblings, 1 reply; 8+ messages in thread
From: Lorenzo Bianconi @ 2026-10-13 10:21 UTC (permalink / raw)
To: Daniel Machon
Cc: Maxime Chevallier, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin, Alexandre Torgue,
Davide Caratti, netdev, linux-arm-kernel, Daniel Thompson
[-- Attachment #1: Type: text/plain, Size: 4973 bytes --]
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.
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@0 1@1 1@2 1@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@riscstar.com>
> > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@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@oss.qualcomm.com>
> >
>
> /Daniel
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^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination
2026-10-13 10:21 ` Lorenzo Bianconi
@ 2026-10-13 10:43 ` Daniel Machon
2026-10-13 12:24 ` Lorenzo Bianconi
0 siblings, 1 reply; 8+ messages in thread
From: Daniel Machon @ 2026-10-13 10:43 UTC (permalink / raw)
To: Lorenzo Bianconi
Cc: Maxime Chevallier, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin, Alexandre Torgue,
Davide Caratti, netdev, linux-arm-kernel, Daniel Thompson
> 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?
>
> 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@0 1@1 1@2 1@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@riscstar.com>
> > > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@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@oss.qualcomm.com>
> > >
> >
> > /Daniel
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination
2026-10-13 10:43 ` Daniel Machon
@ 2026-10-13 12:24 ` Lorenzo Bianconi
0 siblings, 0 replies; 8+ messages in thread
From: Lorenzo Bianconi @ 2026-10-13 12:24 UTC (permalink / raw)
To: Daniel Machon
Cc: Maxime Chevallier, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin, Alexandre Torgue,
Davide Caratti, netdev, linux-arm-kernel, Daniel Thompson
[-- Attachment #1: Type: text/plain, Size: 5970 bytes --]
> > 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@0 1@1 1@2 1@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@riscstar.com>
> > > > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@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@oss.qualcomm.com>
> > > >
> > >
> > > /Daniel
>
>
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination
2026-10-12 21:14 [PATCH net-next] net: stmmac: fix mqprio and cbs combination Lorenzo Bianconi
` (2 preceding siblings ...)
2026-10-13 10:10 ` Daniel Machon
@ 2026-10-13 21:15 ` netdev-bot+sashiko
3 siblings, 0 replies; 8+ messages in thread
From: netdev-bot+sashiko @ 2026-10-13 21:15 UTC (permalink / raw)
To: lorenzo.bianconi
Cc: maxime.chevallier, andrew+netdev, davem, edumazet, kuba, pabeni,
mcoquelin.stm32, alexandre.torgue, dcaratti, netdev,
linux-arm-kernel, daniel
Thank you for your contribution! Sashiko AI review found 1 potential
issue(s) to consider.
Critical: 0 · High: 1 · Medium: 0 · Low: 0
If you believe none of the issues are legitimate, please reply to each
issue of Medium severity or higher and explain why the AI is wrong.
If any of them are legitimate and you plan to respin, please let patchwork
know by including "pw-bot: cr" as a separate line at the end of your reply
(one such reply per series is enough).
- [High] The commit message says the strict-priority scheduler selected
by the channel-mode mqprio offload and the per-queue CBS shaper "are…
--
net: stmmac: fix mqprio and cbs combination
This patch removes the checks that stopped the channel-mode mqprio offload
and the CBS offload from being enabled together. It drops the AVB queue
rejection in tc_mqprio_validate_chan_mode(), the prio_offload check in
tc_setup_cbs(), and the matching AVB check in stmmac_reinit_queues().
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> index ea1f97d6f0bd5..175236ba379d0 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
[ ... ]
> @@ -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;
> - }
> - }
> -
[Severity: High]
The commit message says:
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
Is that true on XGMAC/XLGMAC cores? They use dwmac510_tc_ops, so both
tc_setup_dwmac510_mqprio() and tc_setup_cbs() can be reached on them.
On XGMAC, SP and CBS look like two values of the same per-TC TSA field.
dwxgmac2_prog_mtl_tx_algorithms() rewrites that field on every TC:
drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c:dwxgmac2_prog_mtl_tx_algorithms() {
...
for (i = 0; i < MTL_MAX_TX_QUEUES; i++) {
value = readl(ioaddr + XGMAC_MTL_TCx_ETS_CONTROL(i));
value &= ~XGMAC_TSA;
if (ets)
value |= XGMAC_ETS;
writel(value, ioaddr + XGMAC_MTL_TCx_ETS_CONTROL(i));
}
}
dwxgmac2_config_cbs() turns CBS on by writing the same field:
drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c:dwxgmac2_config_cbs() {
...
value = readl(ioaddr + XGMAC_MTL_TCx_ETS_CONTROL(queue));
value &= ~XGMAC_TSA;
value |= XGMAC_CC | XGMAC_CBS;
writel(value, ioaddr + XGMAC_MTL_TCx_ETS_CONTROL(queue));
}
With this check gone, what happens if a TX queue is already in AVB mode?
One way to get there is a DT mtl-tx-config queue with snps,avb-algorithm.
In that case stmmac_open()->stmmac_mtl_configuration() programs CBS for the
queue when the device is opened.
After that, "tc qdisc replace ... mqprio ... mode channel hw 1" now
succeeds and runs:
tc_setup_dwmac510_mqprio()
tc_mqprio_validate_chan_mode()
tc_mqprio_config_queue_prio()
stmmac_prog_mtl_tx_algorithms(priv, priv->hw, MTL_TX_ALGORITHM_SP)
dwxgmac2_prog_mtl_tx_algorithms()
Would this also clear TSA on the AVB queue and turn CBS off in hardware?
Nothing calls stmmac_configure_cbs() again afterwards. Meanwhile
tx_queues_cfg[].mode_to_use still says MTL_QUEUE_AVB, so the driver state
and the hardware would disagree until the next ndo_open.
Removing mqprio seems to cause the same problem. prio_offload can now be
true while AVB queues exist, and stmmac_reset_tc_mqprio() then does:
stmmac_prog_mtl_tx_algorithms(priv, priv->hw,
priv->plat->tx_sched_algorithm);
On XGMAC this rewrites TSA on every TC again (to ETS or SP). That would
wipe CBS on any AVB queue and not restore it.
The example in the commit message (mqprio first, then the cbs children)
works because config_cbs runs after the SP write.
On dwmac4/EQoS the claim does seem to hold.
dwmac4_prog_mtl_tx_algorithms() only touches MTL_OPERATION_SCHALG_MASK, and
CBS is enabled separately through MTL_ETS_CTRL_AVALG.
The commit in the Fixes: tag added these checks on purpose:
Forcing strict priority conflicts with the CBS algorithm of AVB queues
Should the checks be kept for XGMAC? Or could the mqprio set and reset
paths call stmmac_configure_cbs() again after reprogramming the TX
algorithm?
--
Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261012-stmmac-mqprio-cbs-combo-v1-1-831e323eb4ef%40oss.qualcomm.com
^ permalink raw reply [flat|nested] 8+ messages in thread