ramips: ethernet: unify tx descriptor buffer splitting

A buffer is split into multiple descriptors if it exceeds 16 KB.
Apply the same split for the skb head as well (to deal with corner cases
on fraglist support)

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 8bf17f629c2fa5f29f37eed0315a59c62f6046cf..e0bc0ab818c43d4ce9eb786ca41d71cb8cb7d308 100644 (file)
--- a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -565,40 +565,82 @@ static inline u32 fe_empty_txd(struct fe_tx_ring *ring)
                         (ring->tx_ring_size - 1)));
 }
 
-static int fe_tx_dma_map_page(struct device *dev, struct fe_tx_buf *tx_buf,
-                             struct fe_tx_dma *txd, int idx,
-                             struct page *page, size_t offset, size_t size)
+struct fe_map_state {
+       struct device *dev;
+       struct fe_tx_dma txd;
+       u32 def_txd4;
+       int ring_idx;
+       int i;
+};
+
+static void fe_tx_dma_write_desc(struct fe_tx_ring *ring, struct fe_map_state *st)
 {
+       fe_set_txd(&st->txd, &ring->tx_dma[st->ring_idx]);
+       memset(&st->txd, 0, sizeof(st->txd));
+       st->txd.txd4 = st->def_txd4;
+       st->ring_idx = NEXT_TX_DESP_IDX(st->ring_idx);
+}
+
+static int __fe_tx_dma_map_page(struct fe_tx_ring *ring, struct fe_map_state *st,
+                               struct page *page, size_t offset, size_t size)
+{
+       struct device *dev = st->dev;
+       struct fe_tx_buf *tx_buf;
        dma_addr_t mapped_addr;
 
        mapped_addr = dma_map_page(dev, page, offset, size, DMA_TO_DEVICE);
        if (unlikely(dma_mapping_error(dev, mapped_addr)))
                return -EIO;
 
-       if (idx & 1) {
-               txd->txd3 = mapped_addr;
-               txd->txd2 |= TX_DMA_PLEN1(size);
+       if (st->i && !(st->i & 1))
+           fe_tx_dma_write_desc(ring, st);
+
+       tx_buf = &ring->tx_buf[st->ring_idx];
+       if (st->i & 1) {
+               st->txd.txd3 = mapped_addr;
+               st->txd.txd2 |= TX_DMA_PLEN1(size);
                dma_unmap_addr_set(tx_buf, dma_addr1, mapped_addr);
                dma_unmap_len_set(tx_buf, dma_len1, size);
        } else {
                tx_buf->skb = (struct sk_buff *)DMA_DUMMY_DESC;
-               txd->txd1 = mapped_addr;
-               txd->txd2 = TX_DMA_PLEN0(size);
+               st->txd.txd1 = mapped_addr;
+               st->txd.txd2 = TX_DMA_PLEN0(size);
                dma_unmap_addr_set(tx_buf, dma_addr0, mapped_addr);
                dma_unmap_len_set(tx_buf, dma_len0, size);
        }
+       st->i++;
+
        return 0;
 }
 
-static int fe_tx_dma_map_skb(struct device *dev, struct fe_tx_buf *tx_buf,
-                            struct fe_tx_dma *txd, int idx,
+static int fe_tx_dma_map_page(struct fe_tx_ring *ring, struct fe_map_state *st,
+                             struct page *page, size_t offset, size_t size)
+{
+       int cur_size;
+       int ret;
+
+       while (size > 0) {
+               cur_size = min_t(size_t, size, TX_DMA_BUF_LEN);
+
+               ret = __fe_tx_dma_map_page(ring, st, page, offset, cur_size);
+               if (ret)
+                       return ret;
+
+               size -= cur_size;
+               offset += cur_size;
+       }
+
+       return 0;
+}
+
+static int fe_tx_dma_map_skb(struct fe_tx_ring *ring, struct fe_map_state *st,
                             struct sk_buff *skb)
 {
        struct page *page = virt_to_page(skb->data);
        size_t offset = offset_in_page(skb->data);
        size_t size = skb_headlen(skb);
 
-       return fe_tx_dma_map_page(dev, tx_buf, txd, idx, page, offset, size);
+       return fe_tx_dma_map_page(ring, st, page, offset, size);
 }
 
 static inline struct sk_buff *
@@ -613,41 +655,39 @@ fe_next_frag(struct sk_buff *head, struct sk_buff *skb)
        return NULL;
 }
 
+
 static int fe_tx_map_dma(struct sk_buff *skb, struct net_device *dev,
                         int tx_num, struct fe_tx_ring *ring)
 {
        struct fe_priv *priv = netdev_priv(dev);
-       struct skb_frag_struct *frag;
-       struct fe_tx_dma txd, *ptxd;
-       struct fe_tx_buf *tx_buf;
+       struct fe_map_state st = {
+               .dev = &dev->dev,
+               .ring_idx = ring->tx_next_idx,
+       };
        struct sk_buff *head = skb;
+       struct fe_tx_buf *tx_buf;
        unsigned int nr_frags;
-       u32 def_txd4;
-       int i, j, k, frag_size, frag_map_size, offset;
-
-       tx_buf = &ring->tx_buf[ring->tx_next_idx];
-       memset(tx_buf, 0, sizeof(*tx_buf));
-       memset(&txd, 0, sizeof(txd));
+       int i, j;
 
        /* init tx descriptor */
        if (priv->soc->tx_dma)
-               priv->soc->tx_dma(&txd);
+               priv->soc->tx_dma(&st.txd);
        else
-               txd.txd4 = TX_DMA_DESP4_DEF;
-       def_txd4 = txd.txd4;
+               st.txd.txd4 = TX_DMA_DESP4_DEF;
+       st.def_txd4 = st.txd.txd4;
 
        /* TX Checksum offload */
        if (skb->ip_summed == CHECKSUM_PARTIAL)
-               txd.txd4 |= TX_DMA_CHKSUM;
+               st.txd.txd4 |= TX_DMA_CHKSUM;
 
        /* VLAN header offload */
        if (skb_vlan_tag_present(skb)) {
                u16 tag = skb_vlan_tag_get(skb);
 
                if (IS_ENABLED(CONFIG_SOC_MT7621))
-                       txd.txd4 |= TX_DMA_INS_VLAN_MT7621 | tag;
+                       st.txd.txd4 |= TX_DMA_INS_VLAN_MT7621 | tag;
                else
-                       txd.txd4 |= TX_DMA_INS_VLAN |
+                       st.txd.txd4 |= TX_DMA_INS_VLAN |
                                ((tag >> VLAN_PRIO_SHIFT) << 4) |
                                (tag & 0xF);
        }
@@ -661,75 +701,46 @@ static int fe_tx_map_dma(struct sk_buff *skb, struct net_device *dev,
                }
                if (skb_shinfo(skb)->gso_type &
                                (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)) {
-                       txd.txd4 |= TX_DMA_TSO;
+                       st.txd.txd4 |= TX_DMA_TSO;
                        tcp_hdr(skb)->check = htons(skb_shinfo(skb)->gso_size);
                }
        }
 
-       k = 0;
-       j = ring->tx_next_idx;
-
 next_frag:
-       if (skb_headlen(skb)) {
-               if (fe_tx_dma_map_skb(&dev->dev, tx_buf, &txd, k++, skb))
-                       goto err_dma;
-       }
+       if (skb_headlen(skb) && fe_tx_dma_map_skb(ring, &st, skb))
+               goto err_dma;
 
        /* TX SG offload */
        nr_frags = skb_shinfo(skb)->nr_frags;
        for (i = 0; i < nr_frags; i++) {
-               struct page *page;
+               struct skb_frag_struct *frag;
 
                frag = &skb_shinfo(skb)->frags[i];
-               frag_size = skb_frag_size(frag);
-               offset = frag->page_offset;
-               page = skb_frag_page(frag);
-
-               while (frag_size > 0) {
-                       frag_map_size = min(frag_size, TX_DMA_BUF_LEN);
-                       if (!(k & 0x1)) {
-                               fe_set_txd(&txd, &ring->tx_dma[j]);
-                               memset(&txd, 0, sizeof(txd));
-                               txd.txd4 = def_txd4;
-                               j = NEXT_TX_DESP_IDX(j);
-                               tx_buf = &ring->tx_buf[j];
-                       }
-
-                       if (fe_tx_dma_map_page(&dev->dev, tx_buf, &txd, k++,
-                                              page, offset, frag_map_size))
-                               goto err_dma;
-
-                       frag_size -= frag_map_size;
-                       offset += frag_map_size;
-               }
+               if (fe_tx_dma_map_page(ring, &st, skb_frag_page(frag),
+                                      frag->page_offset, skb_frag_size(frag)))
+                       goto err_dma;
        }
 
        skb = fe_next_frag(head, skb);
-       if (skb) {
-               if (!(k & 0x1)) {
-                       fe_set_txd(&txd, &ring->tx_dma[j]);
-                       memset(&txd, 0, sizeof(txd));
-                       txd.txd4 = def_txd4;
-                       j = NEXT_TX_DESP_IDX(j);
-                       tx_buf = &ring->tx_buf[j];
-               }
+       if (skb)
                goto next_frag;
-       }
 
        /* set last segment */
-       if (k & 0x1)
-               txd.txd2 |= TX_DMA_LS0;
+       if (st.i & 0x1)
+               st.txd.txd2 |= TX_DMA_LS0;
        else
-               txd.txd2 |= TX_DMA_LS1;
-       fe_set_txd(&txd, &ring->tx_dma[j]);
+               st.txd.txd2 |= TX_DMA_LS1;
 
        /* store skb to cleanup */
+       tx_buf = &ring->tx_buf[st.ring_idx];
        tx_buf->skb = head;
 
        netdev_sent_queue(dev, head->len);
        skb_tx_timestamp(head);
 
-       ring->tx_next_idx = NEXT_TX_DESP_IDX(j);
+       fe_tx_dma_write_desc(ring, &st);
+       ring->tx_next_idx = st.ring_idx;
+
        /* make sure that all changes to the dma ring are flushed before we
         * continue
         */
@@ -749,13 +760,10 @@ next_frag:
 err_dma:
        j = ring->tx_next_idx;
        for (i = 0; i < tx_num; i++) {
-               ptxd = &ring->tx_dma[j];
-               tx_buf = &ring->tx_buf[j];
-
                /* unmap dma */
-               fe_txd_unmap(&dev->dev, tx_buf);
+               fe_txd_unmap(&dev->dev, &ring->tx_buf[j]);
+               ring->tx_dma[j].txd2 = TX_DMA_DESP2_DEF;
 
-               ptxd->txd2 = TX_DMA_DESP2_DEF;
                j = NEXT_TX_DESP_IDX(j);
        }
        /* make sure that all changes to the dma ring are flushed before we