bgmac: simplify/optimize rx DMA error handling

Allocate a new buffer before processing the completed one. If allocation
fails, reuse the old buffer.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Acked-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c
index 424a68c..60b5c3c 100644 (file)
--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -386,6 +386,19 @@ static void bgmac_dma_rx_setup_desc(struct bgmac *bgmac,
        dma_desc->ctl1 = cpu_to_le32(ctl1);
 }
 
+static void bgmac_dma_rx_poison_buf(struct device *dma_dev,
+                                   struct bgmac_slot_info *slot)
+{
+       struct bgmac_rx_header *rx = slot->buf + BGMAC_RX_BUF_OFFSET;
+
+       dma_sync_single_for_cpu(dma_dev, slot->dma_addr, BGMAC_RX_BUF_SIZE,
+                               DMA_FROM_DEVICE);
+       rx->len = cpu_to_le16(0xdead);
+       rx->flags = cpu_to_le16(0xbeef);
+       dma_sync_single_for_device(dma_dev, slot->dma_addr, BGMAC_RX_BUF_SIZE,
+                                  DMA_FROM_DEVICE);
+}
+
 static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
                             int weight)
 {
@@ -406,53 +419,35 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
                struct bgmac_rx_header *rx = slot->buf + BGMAC_RX_BUF_OFFSET;
                struct sk_buff *skb;
                void *buf = slot->buf;
+               dma_addr_t dma_addr = slot->dma_addr;
                u16 len, flags;
 
-               /* Unmap buffer to make it accessible to the CPU */
-               dma_sync_single_for_cpu(dma_dev, slot->dma_addr,
-                                       BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
+               do {
+                       /* Prepare new skb as replacement */
+                       if (bgmac_dma_rx_skb_for_slot(bgmac, slot)) {
+                               bgmac_dma_rx_poison_buf(dma_dev, slot);
+                               break;
+                       }
 
-               /* Get info from the header */
-               len = le16_to_cpu(rx->len);
-               flags = le16_to_cpu(rx->flags);
+                       /* Unmap buffer to make it accessible to the CPU */
+                       dma_unmap_single(dma_dev, dma_addr,
+                                        BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
 
-               do {
-                       dma_addr_t old_dma_addr = slot->dma_addr;
-                       int err;
+                       /* Get info from the header */
+                       len = le16_to_cpu(rx->len);
+                       flags = le16_to_cpu(rx->flags);
 
                        /* Check for poison and drop or pass the packet */
                        if (len == 0xdead && flags == 0xbeef) {
                                bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n",
                                          ring->start);
-                               dma_sync_single_for_device(dma_dev,
-                                                          slot->dma_addr,
-                                                          BGMAC_RX_BUF_SIZE,
-                                                          DMA_FROM_DEVICE);
+                               put_page(virt_to_head_page(buf));
                                break;
                        }
 
                        /* Omit CRC. */
                        len -= ETH_FCS_LEN;
 
-                       /* Prepare new skb as replacement */
-                       err = bgmac_dma_rx_skb_for_slot(bgmac, slot);
-                       if (err) {
-                               /* Poison the old skb */
-                               rx->len = cpu_to_le16(0xdead);
-                               rx->flags = cpu_to_le16(0xbeef);
-
-                               dma_sync_single_for_device(dma_dev,
-                                                          slot->dma_addr,
-                                                          BGMAC_RX_BUF_SIZE,
-                                                          DMA_FROM_DEVICE);
-                               break;
-                       }
-                       bgmac_dma_rx_setup_desc(bgmac, ring, ring->start);
-
-                       /* Unmap old skb, we'll pass it to the netfif */
-                       dma_unmap_single(dma_dev, old_dma_addr,
-                                        BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
-
                        skb = build_skb(buf, BGMAC_RX_ALLOC_SIZE);
                        skb_put(skb, BGMAC_RX_FRAME_OFFSET +
                                BGMAC_RX_BUF_OFFSET + len);
@@ -465,6 +460,8 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
                        handled++;
                } while (0);
 
+               bgmac_dma_rx_setup_desc(bgmac, ring, ring->start);
+
                if (++ring->start >= BGMAC_RX_RING_SLOTS)
                        ring->start = 0;
 
@@ -532,14 +529,14 @@ static void bgmac_dma_rx_ring_free(struct bgmac *bgmac,
 
        for (i = 0; i < ring->num_slots; i++) {
                slot = &ring->slots[i];
-               if (!slot->buf)
+               if (!slot->dma_addr)
                        continue;
 
-               if (slot->dma_addr)
-                       dma_unmap_single(dma_dev, slot->dma_addr,
-                                        BGMAC_RX_BUF_SIZE,
-                                        DMA_FROM_DEVICE);
+               dma_unmap_single(dma_dev, slot->dma_addr,
+                                BGMAC_RX_BUF_SIZE,
+                                DMA_FROM_DEVICE);
                put_page(virt_to_head_page(slot->buf));
+               slot->dma_addr = 0;
        }
 }