Re: [PATCH net-next v4 5/7] net: stmmac: support fp parameter of tc-mqprio

On Tue, Aug 20, 2024 at 05:38:33PM +0800, Furong Xu wrote:

+static int tc_setup_mqprio(struct stmmac_priv *priv,
+			   struct tc_mqprio_qopt_offload *mqprio)
+{
+	struct netlink_ext_ack *extack = mqprio->extack;
+	struct tc_mqprio_qopt *qopt = &mqprio->qopt;
+	struct net_device *ndev = priv->dev;
+	int num_stack_tx_queues = 0;
+	int num_tc = qopt->num_tc;
+	u16 offset, count;
+	int tc, err;
+
+	if (!num_tc) {
+		stmmac_reset_tc_mqprio(ndev, extack);
+		return 0;
+	}
+
+	if (mqprio->preemptible_tcs && !ethtool_dev_mm_supported(ndev)) {
+		NL_SET_ERR_MSG_MOD(extack, "Device does not support preemption");
+		return -EOPNOTSUPP;
+	}

When I said that "this condition is dealt with by the core, now"
https://lore.kernel.org/netdev/20240819114242.2m6okk7bq64e437c@skbuf/ (local)
I meant that the driver doesn't need to check anything - the check has
already run once, in the Qdisc layer. See taprio_parse_tc_entries() and
mqprio_parse_tc_entries(). I was not asking to insert this test, just to
completely remove, rather than adapt, the entire block:

	if (fpe && !priv->dma_cap.fpesel) {
		mutex_unlock(&priv->est_lock);
		return -EOPNOTSUPP;
	}