Merge branch 'net-airoha-fix-airoha_qdma_cleanup_tx_queue-processing'

Lorenzo Bianconi says:

====================
net: airoha: Fix airoha_qdma_cleanup_tx_queue() processing

Add missing bits in airoha_qdma_cleanup_tx_queue routine.
Fix airoha_qdma_cleanup_tx_queue processing errors intorduced in commit
'3f47e67dff1f7 ("net: airoha: Add the capability to consume out-of-order
DMA tx descriptors")'.

v3: https://lore.kernel.org/r/20260416-airoha_qdma_cleanup_tx_queue-fix-net-v3-0-2b69f5788580@kernel.org
v2: https://lore.kernel.org/r/20260414-airoha_qdma_cleanup_tx_queue-fix-net-v2-1-875de57cc022@kernel.org
v1: https://lore.kernel.org/r/20260410-airoha_qdma_cleanup_tx_queue-fix-net-v1-1-b7171c8f1e78@kernel.org
====================

Link: https://patch.msgid.link/20260417-airoha_qdma_cleanup_tx_queue-fix-net-v4-0-e04bcc2c9642@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Paolo Abeni

drivers/net/ethernet/airoha/airoha_eth.c

@@ -978,27 +978,27 @@ static int airoha_qdma_init_tx_queue(struct airoha_queue *q,
 	dma_addr_t dma_addr;
 
 	spin_lock_init(&q->lock);
-	q->ndesc = size;
 	q->qdma = qdma;
 	q->free_thr = 1 + MAX_SKB_FRAGS;
 	INIT_LIST_HEAD(&q->tx_list);
 
-	q->entry = devm_kzalloc(eth->dev, q->ndesc * sizeof(*q->entry),
+	q->entry = devm_kzalloc(eth->dev, size * sizeof(*q->entry),
 				GFP_KERNEL);
 	if (!q->entry)
 		return -ENOMEM;
 
-	q->desc = dmam_alloc_coherent(eth->dev, q->ndesc * sizeof(*q->desc),
+	q->desc = dmam_alloc_coherent(eth->dev, size * sizeof(*q->desc),
 				      &dma_addr, GFP_KERNEL);
 	if (!q->desc)
 		return -ENOMEM;
 
-	for (i = 0; i < q->ndesc; i++) {
+	for (i = 0; i < size; i++) {
 		u32 val = FIELD_PREP(QDMA_DESC_DONE_MASK, 1);
 
 		list_add_tail(&q->entry[i].list, &q->tx_list);
 		WRITE_ONCE(q->desc[i].ctrl, cpu_to_le32(val));
 	}
+	q->ndesc = size;
 
 	/* xmit ring drop default setting */
 	airoha_qdma_set(qdma, REG_TX_RING_BLOCKING(qid),
@@ -1063,12 +1063,15 @@ static int airoha_qdma_init_tx(struct airoha_qdma *qdma)
 
 static void airoha_qdma_cleanup_tx_queue(struct airoha_queue *q)
 {
-	struct airoha_eth *eth = q->qdma->eth;
-	int i;
+	struct airoha_qdma *qdma = q->qdma;
+	struct airoha_eth *eth = qdma->eth;
+	int i, qid = q - &qdma->q_tx[0];
+	u16 index = 0;
 
 	spin_lock_bh(&q->lock);
 	for (i = 0; i < q->ndesc; i++) {
 		struct airoha_queue_entry *e = &q->entry[i];
+		struct airoha_qdma_desc *desc = &q->desc[i];
 
 		if (!e->dma_addr)
 			continue;
@@ -1079,8 +1082,33 @@ static void airoha_qdma_cleanup_tx_queue(struct airoha_queue *q)
 		e->dma_addr = 0;
 		e->skb = NULL;
 		list_add_tail(&e->list, &q->tx_list);
+
+		/* Reset DMA descriptor */
+		WRITE_ONCE(desc->ctrl, 0);
+		WRITE_ONCE(desc->addr, 0);
+		WRITE_ONCE(desc->data, 0);
+		WRITE_ONCE(desc->msg0, 0);
+		WRITE_ONCE(desc->msg1, 0);
+		WRITE_ONCE(desc->msg2, 0);
+
 		q->queued--;
 	}
+
+	if (!list_empty(&q->tx_list)) {
+		struct airoha_queue_entry *e;
+
+		e = list_first_entry(&q->tx_list, struct airoha_queue_entry,
+				     list);
+		index = e - q->entry;
+	}
+	/* Set TX_DMA_IDX to TX_CPU_IDX to notify the hw the QDMA TX ring is
+	 * empty.
+	 */
+	airoha_qdma_rmw(qdma, REG_TX_CPU_IDX(qid), TX_RING_CPU_IDX_MASK,
+			FIELD_PREP(TX_RING_CPU_IDX_MASK, index));
+	airoha_qdma_rmw(qdma, REG_TX_DMA_IDX(qid), TX_RING_DMA_IDX_MASK,
+			FIELD_PREP(TX_RING_DMA_IDX_MASK, index));
+
 	spin_unlock_bh(&q->lock);
 }