[openwrt/openwrt] airoha: backport patch fixing out of order DMA for ethernet driver
LEDE Commits
lede-commits at lists.infradead.org
Wed Nov 12 01:13:44 PST 2025
ansuel pushed a commit to openwrt/openwrt.git, branch openwrt-24.10:
https://git.openwrt.org/d804c3110b2d9290089f6b719092e0dc762c687d
commit d804c3110b2d9290089f6b719092e0dc762c687d
Author: Christian Marangi <ansuelsmth at gmail.com>
AuthorDate: Mon Nov 10 19:27:11 2025 +0100
airoha: backport patch fixing out of order DMA for ethernet driver
Backport upstream patch fixing out of order DMA access for ethernet
driver. This is relevant in the context of QoS when packets doesn't
follow linear handling by QDMA HW.
(cherry picked from commit 3169ffa4c74d7e0a891be29d4ca3a2a4bf218884)
[ fix conflict errors ]
Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
...Add-the-capability-to-consume-out-of-orde.patch | 245 +++++++++++++++++++++
1 file changed, 245 insertions(+)
diff --git a/target/linux/airoha/patches-6.6/108-v6.19-net-airoha-Add-the-capability-to-consume-out-of-orde.patch b/target/linux/airoha/patches-6.6/108-v6.19-net-airoha-Add-the-capability-to-consume-out-of-orde.patch
new file mode 100644
index 0000000000..b09ebd57b4
--- /dev/null
+++ b/target/linux/airoha/patches-6.6/108-v6.19-net-airoha-Add-the-capability-to-consume-out-of-orde.patch
@@ -0,0 +1,245 @@
+From 3f47e67dff1f7266e112c50313d63824f6f17102 Mon Sep 17 00:00:00 2001
+From: Lorenzo Bianconi <lorenzo at kernel.org>
+Date: Thu, 6 Nov 2025 13:53:23 +0100
+Subject: [PATCH] net: airoha: Add the capability to consume out-of-order DMA
+ tx descriptors
+
+EN7581 and AN7583 SoCs are capable of DMA mapping non-linear tx skbs on
+non-consecutive DMA descriptors. This feature is useful when multiple
+flows are queued on the same hw tx queue since it allows to fully utilize
+the available tx DMA descriptors and to avoid the starvation of
+high-priority flow we have in the current codebase due to head-of-line
+blocking introduced by low-priority flows.
+
+Tested-by: Xuegang Lu <xuegang.lu at airoha.com>
+Reviewed-by: Jacob Keller <jacob.e.keller at intel.com>
+Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
+Link: https://patch.msgid.link/20251106-airoha-tx-linked-list-v2-1-0706d4a322bd@kernel.org
+Signed-off-by: Jakub Kicinski <kuba at kernel.org>
+---
+ drivers/net/ethernet/airoha/airoha_eth.c | 85 +++++++++++-------------
+ drivers/net/ethernet/airoha/airoha_eth.h | 7 +-
+ 2 files changed, 45 insertions(+), 47 deletions(-)
+
+--- a/drivers/net/ethernet/airoha/airoha_eth.c
++++ b/drivers/net/ethernet/airoha/airoha_eth.c
+@@ -892,19 +892,13 @@ static int airoha_qdma_tx_napi_poll(stru
+
+ dma_unmap_single(eth->dev, e->dma_addr, e->dma_len,
+ DMA_TO_DEVICE);
+- memset(e, 0, sizeof(*e));
++ e->dma_addr = 0;
++ list_add_tail(&e->list, &q->tx_list);
++
+ WRITE_ONCE(desc->msg0, 0);
+ WRITE_ONCE(desc->msg1, 0);
+ q->queued--;
+
+- /* completion ring can report out-of-order indexes if hw QoS
+- * is enabled and packets with different priority are queued
+- * to same DMA ring. Take into account possible out-of-order
+- * reports incrementing DMA ring tail pointer
+- */
+- while (q->tail != q->head && !q->entry[q->tail].dma_addr)
+- q->tail = (q->tail + 1) % q->ndesc;
+-
+ if (skb) {
+ u16 queue = skb_get_queue_mapping(skb);
+ struct netdev_queue *txq;
+@@ -949,6 +943,7 @@ static int airoha_qdma_init_tx_queue(str
+ 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),
+ GFP_KERNEL);
+@@ -961,9 +956,9 @@ static int airoha_qdma_init_tx_queue(str
+ return -ENOMEM;
+
+ for (i = 0; i < q->ndesc; i++) {
+- u32 val;
++ u32 val = FIELD_PREP(QDMA_DESC_DONE_MASK, 1);
+
+- 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));
+ }
+
+@@ -973,9 +968,9 @@ static int airoha_qdma_init_tx_queue(str
+
+ airoha_qdma_wr(qdma, REG_TX_RING_BASE(qid), dma_addr);
+ airoha_qdma_rmw(qdma, REG_TX_CPU_IDX(qid), TX_RING_CPU_IDX_MASK,
+- FIELD_PREP(TX_RING_CPU_IDX_MASK, q->head));
++ FIELD_PREP(TX_RING_CPU_IDX_MASK, 0));
+ airoha_qdma_rmw(qdma, REG_TX_DMA_IDX(qid), TX_RING_DMA_IDX_MASK,
+- FIELD_PREP(TX_RING_DMA_IDX_MASK, q->head));
++ FIELD_PREP(TX_RING_DMA_IDX_MASK, 0));
+
+ return 0;
+ }
+@@ -1031,17 +1026,21 @@ static int airoha_qdma_init_tx(struct ai
+ static void airoha_qdma_cleanup_tx_queue(struct airoha_queue *q)
+ {
+ struct airoha_eth *eth = q->qdma->eth;
++ int i;
+
+ spin_lock_bh(&q->lock);
+- while (q->queued) {
+- struct airoha_queue_entry *e = &q->entry[q->tail];
++ for (i = 0; i < q->ndesc; i++) {
++ struct airoha_queue_entry *e = &q->entry[i];
++
++ if (!e->dma_addr)
++ continue;
+
+ dma_unmap_single(eth->dev, e->dma_addr, e->dma_len,
+ DMA_TO_DEVICE);
+ dev_kfree_skb_any(e->skb);
++ e->dma_addr = 0;
+ e->skb = NULL;
+-
+- q->tail = (q->tail + 1) % q->ndesc;
++ list_add_tail(&e->list, &q->tx_list);
+ q->queued--;
+ }
+ spin_unlock_bh(&q->lock);
+@@ -1883,20 +1882,6 @@ static u32 airoha_get_dsa_tag(struct sk_
+ #endif
+ }
+
+-static bool airoha_dev_tx_queue_busy(struct airoha_queue *q, u32 nr_frags)
+-{
+- u32 tail = q->tail <= q->head ? q->tail + q->ndesc : q->tail;
+- u32 index = q->head + nr_frags;
+-
+- /* completion napi can free out-of-order tx descriptors if hw QoS is
+- * enabled and packets with different priorities are queued to the same
+- * DMA ring. Take into account possible out-of-order reports checking
+- * if the tx queue is full using circular buffer head/tail pointers
+- * instead of the number of queued packets.
+- */
+- return index >= tail;
+-}
+-
+ static int airoha_get_fe_port(struct airoha_gdm_port *port)
+ {
+ struct airoha_qdma *qdma = port->qdma;
+@@ -1919,8 +1904,10 @@ static netdev_tx_t airoha_dev_xmit(struc
+ struct airoha_gdm_port *port = netdev_priv(dev);
+ struct airoha_qdma *qdma = port->qdma;
+ u32 nr_frags, tag, msg0, msg1, len;
++ struct airoha_queue_entry *e;
+ struct netdev_queue *txq;
+ struct airoha_queue *q;
++ LIST_HEAD(tx_list);
+ void *data;
+ int i, qid;
+ u16 index;
+@@ -1966,7 +1953,7 @@ static netdev_tx_t airoha_dev_xmit(struc
+ txq = netdev_get_tx_queue(dev, qid);
+ nr_frags = 1 + skb_shinfo(skb)->nr_frags;
+
+- if (airoha_dev_tx_queue_busy(q, nr_frags)) {
++ if (q->queued + nr_frags >= q->ndesc) {
+ /* not enough space in the queue */
+ netif_tx_stop_queue(txq);
+ spin_unlock_bh(&q->lock);
+@@ -1975,11 +1962,13 @@ static netdev_tx_t airoha_dev_xmit(struc
+
+ len = skb_headlen(skb);
+ data = skb->data;
+- index = q->head;
++
++ e = list_first_entry(&q->tx_list, struct airoha_queue_entry,
++ list);
++ index = e - q->entry;
+
+ for (i = 0; i < nr_frags; i++) {
+ struct airoha_qdma_desc *desc = &q->desc[index];
+- struct airoha_queue_entry *e = &q->entry[index];
+ skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+ dma_addr_t addr;
+ u32 val;
+@@ -1989,7 +1978,14 @@ static netdev_tx_t airoha_dev_xmit(struc
+ if (unlikely(dma_mapping_error(dev->dev.parent, addr)))
+ goto error_unmap;
+
+- index = (index + 1) % q->ndesc;
++ list_move_tail(&e->list, &tx_list);
++ e->skb = i ? NULL : skb;
++ e->dma_addr = addr;
++ e->dma_len = len;
++
++ e = list_first_entry(&q->tx_list, struct airoha_queue_entry,
++ list);
++ index = e - q->entry;
+
+ val = FIELD_PREP(QDMA_DESC_LEN_MASK, len);
+ if (i < nr_frags - 1)
+@@ -2002,15 +1998,9 @@ static netdev_tx_t airoha_dev_xmit(struc
+ WRITE_ONCE(desc->msg1, cpu_to_le32(msg1));
+ WRITE_ONCE(desc->msg2, cpu_to_le32(0xffff));
+
+- e->skb = i ? NULL : skb;
+- e->dma_addr = addr;
+- e->dma_len = len;
+-
+ data = skb_frag_address(frag);
+ len = skb_frag_size(frag);
+ }
+-
+- q->head = index;
+ q->queued += i;
+
+ skb_tx_timestamp(skb);
+@@ -2019,7 +2009,7 @@ static netdev_tx_t airoha_dev_xmit(struc
+ 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));
++ FIELD_PREP(TX_RING_CPU_IDX_MASK, index));
+
+ if (q->ndesc - q->queued < q->free_thr)
+ netif_tx_stop_queue(txq);
+@@ -2029,10 +2019,13 @@ static netdev_tx_t airoha_dev_xmit(struc
+ return NETDEV_TX_OK;
+
+ error_unmap:
+- for (i--; i >= 0; i--) {
+- index = (q->head + i) % q->ndesc;
+- dma_unmap_single(dev->dev.parent, q->entry[index].dma_addr,
+- q->entry[index].dma_len, DMA_TO_DEVICE);
++ while (!list_empty(&tx_list)) {
++ e = list_first_entry(&tx_list, struct airoha_queue_entry,
++ list);
++ dma_unmap_single(dev->dev.parent, e->dma_addr, e->dma_len,
++ DMA_TO_DEVICE);
++ e->dma_addr = 0;
++ list_move_tail(&e->list, &q->tx_list);
+ }
+
+ spin_unlock_bh(&q->lock);
+--- a/drivers/net/ethernet/airoha/airoha_eth.h
++++ b/drivers/net/ethernet/airoha/airoha_eth.h
+@@ -169,7 +169,10 @@ enum trtcm_param {
+ struct airoha_queue_entry {
+ union {
+ void *buf;
+- struct sk_buff *skb;
++ struct {
++ struct list_head list;
++ struct sk_buff *skb;
++ };
+ };
+ dma_addr_t dma_addr;
+ u16 dma_len;
+@@ -193,6 +196,8 @@ struct airoha_queue {
+ struct napi_struct napi;
+ struct page_pool *page_pool;
+ struct sk_buff *skb;
++
++ struct list_head tx_list;
+ };
+
+ struct airoha_tx_irq_queue {
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