Refactor mvneta_rx_swbm code introducing mvneta_swbm_rx_frame and
mvneta_swbm_add_rx_fragment routines. Rely on build_skb in oreder to
allocate skb since the previous patch introduced buffer recycling using
the page_pool API.
This patch fixes even an issue in the original driver where dma buffers
are accessed before dma sync

Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
---
 drivers/net/ethernet/marvell/mvneta.c | 198 ++++++++++++++------------
 1 file changed, 104 insertions(+), 94 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c 
b/drivers/net/ethernet/marvell/mvneta.c
index 31cecc1ed848..79a6bac0192b 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -323,6 +323,11 @@
              ETH_HLEN + ETH_FCS_LEN,                        \
              cache_line_size())
 
+#define MVNETA_SKB_PAD (SKB_DATA_ALIGN(sizeof(struct skb_shared_info) + \
+                        NET_SKB_PAD))
+#define MVNETA_SKB_SIZE(len)   (SKB_DATA_ALIGN(len) + MVNETA_SKB_PAD)
+#define MVNETA_MAX_RX_BUF_SIZE (PAGE_SIZE - MVNETA_SKB_PAD)
+
 #define IS_TSO_HEADER(txq, addr) \
        ((addr >= txq->tso_hdrs_phys) && \
         (addr < txq->tso_hdrs_phys + txq->size * TSO_HEADER_SIZE))
@@ -646,7 +651,6 @@ static int txq_number = 8;
 static int rxq_def;
 
 static int rx_copybreak __read_mostly = 256;
-static int rx_header_size __read_mostly = 128;
 
 /* HW BM need that each port be identify by a unique ID */
 static int global_port_id;
@@ -1942,30 +1946,102 @@ int mvneta_rx_refill_queue(struct mvneta_port *pp, 
struct mvneta_rx_queue *rxq)
        return i;
 }
 
+static int
+mvneta_swbm_rx_frame(struct mvneta_port *pp,
+                    struct mvneta_rx_desc *rx_desc,
+                    struct mvneta_rx_queue *rxq,
+                    struct page *page)
+{
+       unsigned char *data = page_address(page);
+       int data_len = -MVNETA_MH_SIZE, len;
+       struct net_device *dev = pp->dev;
+       enum dma_data_direction dma_dir;
+
+       if (MVNETA_SKB_SIZE(rx_desc->data_size) > PAGE_SIZE) {
+               len = MVNETA_MAX_RX_BUF_SIZE;
+               data_len += len;
+       } else {
+               len = rx_desc->data_size;
+               data_len += len - ETH_FCS_LEN;
+       }
+
+       dma_dir = page_pool_get_dma_dir(rxq->page_pool);
+       dma_sync_single_range_for_cpu(dev->dev.parent,
+                                     rx_desc->buf_phys_addr, 0,
+                                     len, dma_dir);
+
+       rxq->skb = build_skb(data, PAGE_SIZE);
+       if (unlikely(!rxq->skb)) {
+               netdev_err(dev,
+                          "Can't allocate skb on queue %d\n",
+                          rxq->id);
+               dev->stats.rx_dropped++;
+               rxq->skb_alloc_err++;
+               return -ENOMEM;
+       }
+       page_pool_release_page(rxq->page_pool, page);
+
+       skb_reserve(rxq->skb, MVNETA_MH_SIZE + NET_SKB_PAD);
+       skb_put(rxq->skb, data_len);
+       mvneta_rx_csum(pp, rx_desc->status, rxq->skb);
+
+       rxq->left_size = rx_desc->data_size - len;
+       rx_desc->buf_phys_addr = 0;
+
+       return 0;
+}
+
+static void
+mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
+                           struct mvneta_rx_desc *rx_desc,
+                           struct mvneta_rx_queue *rxq,
+                           struct page *page)
+{
+       struct net_device *dev = pp->dev;
+       enum dma_data_direction dma_dir;
+       int data_len, len;
+
+       if (rxq->left_size > MVNETA_MAX_RX_BUF_SIZE) {
+               len = MVNETA_MAX_RX_BUF_SIZE;
+               data_len = len;
+       } else {
+               len = rxq->left_size;
+               data_len = len - ETH_FCS_LEN;
+       }
+       dma_dir = page_pool_get_dma_dir(rxq->page_pool);
+       dma_sync_single_range_for_cpu(dev->dev.parent,
+                                     rx_desc->buf_phys_addr, 0,
+                                     len, dma_dir);
+       if (data_len > 0) {
+               /* refill descriptor with new buffer later */
+               skb_add_rx_frag(rxq->skb,
+                               skb_shinfo(rxq->skb)->nr_frags,
+                               page, NET_SKB_PAD, data_len,
+                               PAGE_SIZE);
+
+               page_pool_release_page(rxq->page_pool, page);
+               rx_desc->buf_phys_addr = 0;
+       }
+       rxq->left_size -= len;
+}
+
 /* Main rx processing when using software buffer management */
 static int mvneta_rx_swbm(struct napi_struct *napi,
                          struct mvneta_port *pp, int budget,
                          struct mvneta_rx_queue *rxq)
 {
-       struct net_device *dev = pp->dev;
-       int rx_todo, rx_proc;
-       int refill = 0;
-       u32 rcvd_pkts = 0;
-       u32 rcvd_bytes = 0;
+       int rcvd_pkts = 0, rcvd_bytes = 0;
+       int rx_pending, refill, done = 0;
 
        /* Get number of received packets */
-       rx_todo = mvneta_rxq_busy_desc_num_get(pp, rxq);
-       rx_proc = 0;
+       rx_pending = mvneta_rxq_busy_desc_num_get(pp, rxq);
 
        /* Fairness NAPI loop */
-       while ((rcvd_pkts < budget) && (rx_proc < rx_todo)) {
+       while (done < budget && done < rx_pending) {
                struct mvneta_rx_desc *rx_desc = mvneta_rxq_next_desc_get(rxq);
                unsigned char *data;
                struct page *page;
-               dma_addr_t phys_addr;
-               u32 rx_status, index;
-               int rx_bytes, skb_size, copy_size;
-               int frag_num, frag_size, frag_offset;
+               int index;
 
                index = rx_desc - rxq->descs;
                page = (struct page *)rxq->buf_virt_addr[index];
@@ -1973,98 +2049,33 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
                /* Prefetch header */
                prefetch(data);
 
-               phys_addr = rx_desc->buf_phys_addr;
-               rx_status = rx_desc->status;
-               rx_proc++;
                rxq->refill_num++;
+               done++;
+
+               if (rx_desc->status & MVNETA_RXD_FIRST_DESC) {
+                       int err;
 
-               if (rx_status & MVNETA_RXD_FIRST_DESC) {
                        /* Check errors only for FIRST descriptor */
-                       if (rx_status & MVNETA_RXD_ERR_SUMMARY) {
+                       if (rx_desc->status & MVNETA_RXD_ERR_SUMMARY) {
                                mvneta_rx_error(pp, rx_desc);
-                               dev->stats.rx_errors++;
+                               pp->dev->stats.rx_errors++;
                                /* leave the descriptor untouched */
                                continue;
                        }
-                       rx_bytes = rx_desc->data_size -
-                                  (ETH_FCS_LEN + MVNETA_MH_SIZE);
 
-                       /* Allocate small skb for each new packet */
-                       skb_size = max(rx_copybreak, rx_header_size);
-                       rxq->skb = netdev_alloc_skb_ip_align(dev, skb_size);
-                       if (unlikely(!rxq->skb)) {
-                               netdev_err(dev,
-                                          "Can't allocate skb on queue %d\n",
-                                          rxq->id);
-                               dev->stats.rx_dropped++;
-                               rxq->skb_alloc_err++;
+                       err = mvneta_swbm_rx_frame(pp, rx_desc, rxq, page);
+                       if (err)
                                continue;
-                       }
-                       copy_size = min(skb_size, rx_bytes);
-
-                       /* Copy data from buffer to SKB, skip Marvell header */
-                       memcpy(rxq->skb->data, data + MVNETA_MH_SIZE,
-                              copy_size);
-                       skb_put(rxq->skb, copy_size);
-                       rxq->left_size = rx_bytes - copy_size;
-
-                       mvneta_rx_csum(pp, rx_status, rxq->skb);
-                       if (rxq->left_size == 0) {
-                               int size = copy_size + MVNETA_MH_SIZE;
-
-                               dma_sync_single_range_for_cpu(dev->dev.parent,
-                                                             phys_addr, 0,
-                                                             size,
-                                                             DMA_FROM_DEVICE);
-
-                               /* leave the descriptor and buffer untouched */
-                       } else {
-                               /* refill descriptor with new buffer later */
-                               rx_desc->buf_phys_addr = 0;
-
-                               frag_num = 0;
-                               frag_offset = copy_size + MVNETA_MH_SIZE;
-                               frag_size = min(rxq->left_size,
-                                               (int)(PAGE_SIZE - frag_offset));
-                               skb_add_rx_frag(rxq->skb, frag_num, page,
-                                               frag_offset, frag_size,
-                                               PAGE_SIZE);
-                               page_pool_release_page(rxq->page_pool, page);
-                               rxq->left_size -= frag_size;
-                       }
                } else {
-                       /* Middle or Last descriptor */
                        if (unlikely(!rxq->skb)) {
                                pr_debug("no skb for rx_status 0x%x\n",
-                                        rx_status);
+                                        rx_desc->status);
                                continue;
                        }
-                       if (!rxq->left_size) {
-                               /* last descriptor has only FCS */
-                               /* and can be discarded */
-                               dma_sync_single_range_for_cpu(dev->dev.parent,
-                                                             phys_addr, 0,
-                                                             ETH_FCS_LEN,
-                                                             DMA_FROM_DEVICE);
-                               /* leave the descriptor and buffer untouched */
-                       } else {
-                               /* refill descriptor with new buffer later */
-                               rx_desc->buf_phys_addr = 0;
-
-                               frag_num = skb_shinfo(rxq->skb)->nr_frags;
-                               frag_offset = 0;
-                               frag_size = min(rxq->left_size,
-                                               (int)(PAGE_SIZE - frag_offset));
-                               skb_add_rx_frag(rxq->skb, frag_num, page,
-                                               frag_offset, frag_size,
-                                               PAGE_SIZE);
-
-                               page_pool_release_page(rxq->page_pool, page);
-                               rxq->left_size -= frag_size;
-                       }
+                       mvneta_swbm_add_rx_fragment(pp, rx_desc, rxq, page);
                } /* Middle or Last descriptor */
 
-               if (!(rx_status & MVNETA_RXD_LAST_DESC))
+               if (!(rx_desc->status & MVNETA_RXD_LAST_DESC))
                        /* no last descriptor this time */
                        continue;
 
@@ -2080,13 +2091,12 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
                rcvd_bytes += rxq->skb->len;
 
                /* Linux processing */
-               rxq->skb->protocol = eth_type_trans(rxq->skb, dev);
+               rxq->skb->protocol = eth_type_trans(rxq->skb, pp->dev);
 
                napi_gro_receive(napi, rxq->skb);
 
                /* clean uncomplete skb pointer in queue */
                rxq->skb = NULL;
-               rxq->left_size = 0;
        }
 
        mvneta_update_stats(pp, rcvd_pkts, rcvd_bytes, false);
@@ -2095,7 +2105,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
        refill = mvneta_rx_refill_queue(pp, rxq);
 
        /* Update rxq management counters */
-       mvneta_rxq_desc_num_update(pp, rxq, rx_proc, refill);
+       mvneta_rxq_desc_num_update(pp, rxq, done, refill);
 
        return rcvd_pkts;
 }
@@ -2946,7 +2956,7 @@ static void mvneta_rxq_hw_init(struct mvneta_port *pp,
                /* Set Offset */
                mvneta_rxq_offset_set(pp, rxq, 0);
                mvneta_rxq_buf_size_set(pp, rxq, PAGE_SIZE < SZ_64K ?
-                                       PAGE_SIZE :
+                                       MVNETA_MAX_RX_BUF_SIZE :
                                        MVNETA_RX_BUF_SIZE(pp->pkt_size));
                mvneta_rxq_bm_disable(pp, rxq);
                mvneta_rxq_fill(pp, rxq, rxq->size);
@@ -4656,7 +4666,7 @@ static int mvneta_probe(struct platform_device *pdev)
        SET_NETDEV_DEV(dev, &pdev->dev);
 
        pp->id = global_port_id++;
-       pp->rx_offset_correction = 0; /* not relevant for SW BM */
+       pp->rx_offset_correction = NET_SKB_PAD;
 
        /* Obtain access to BM resources if enabled and already initialized */
        bm_node = of_parse_phandle(dn, "buffer-manager", 0);
-- 
2.21.0

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