[PATCH net-next] net: stmmac: fix mqprio and cbs combination

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 <redacted>
Signed-off-by: Lorenzo Bianconi <redacted>
---
 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 [off-list ref]