net: airoha: Implement BQL support

Introduce BQL support in the airoha_eth driver reporting to the kernel
info about tx hw DMA queues in order to avoid bufferbloat and keep the
latency small.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20241012-en7581-bql-v2-1-4deb4efdb60b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mediatek/airoha_eth.c

@@ -1709,9 +1709,11 @@ static int airoha_qdma_tx_napi_poll(struct napi_struct *napi, int budget)
 			WRITE_ONCE(desc->msg1, 0);
 
 			if (skb) {
+				u16 queue = skb_get_queue_mapping(skb);
 				struct netdev_queue *txq;
 
-				txq = netdev_get_tx_queue(skb->dev, qid);
+				txq = netdev_get_tx_queue(skb->dev, queue);
+				netdev_tx_completed_queue(txq, 1, skb->len);
 				if (netif_tx_queue_stopped(txq) &&
 				    q->ndesc - q->queued >= q->free_thr)
 					netif_tx_wake_queue(txq);
@@ -2487,7 +2489,9 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
 	q->queued += i;
 
 	skb_tx_timestamp(skb);
-	if (!netdev_xmit_more())
+	netdev_tx_sent_queue(txq, skb->len);
+
+	if (netif_xmit_stopped(txq) || !netdev_xmit_more())
 		airoha_qdma_rmw(qdma, REG_TX_CPU_IDX(qid),
 				TX_RING_CPU_IDX_MASK,
 				FIELD_PREP(TX_RING_CPU_IDX_MASK, q->head));