From: Felix Fietkau <nbd@openwrt.org>
Date: Sun, 12 Apr 2015 22:23:07 +0200
-Subject: [PATCH] bgmac: simplify rx DMA error handling
+Subject: [PATCH] bgmac: simplify/optimize rx DMA error handling
-Unmap the DMA buffer before checking it. If it is poisoned, map it again
-and pass it back to the hardware.
+Allocate a new buffer before processing the completed one. If allocation
+fails, reuse the old buffer.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
-@@ -405,25 +405,20 @@ static int bgmac_dma_rx_read(struct bgma
+@@ -386,6 +386,19 @@ static void bgmac_dma_rx_setup_desc(stru
+ 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 bgma
+ 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 */
+- /* 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);
-+ dma_unmap_single(dma_dev, slot->dma_addr,
-+ BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
-
- /* Get info from the header */
- len = le16_to_cpu(rx->len);
- flags = le16_to_cpu(rx->flags);
-
+-
+- /* Get info from the header */
+- len = le16_to_cpu(rx->len);
+- flags = le16_to_cpu(rx->flags);
+-
do {
- dma_addr_t old_dma_addr = slot->dma_addr;
- int err;
+- int err;
++ /* Prepare new skb as replacement */
++ if (bgmac_dma_rx_skb_for_slot(bgmac, slot)) {
++ bgmac_dma_rx_poison_buf(dma_dev, slot);
++ break;
++ }
++
++ /* Unmap buffer to make it accessible to the CPU */
++ dma_unmap_single(dma_dev, dma_addr,
++ BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
++
++ /* 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) {
- slot->dma_addr,
- BGMAC_RX_BUF_SIZE,
- DMA_FROM_DEVICE);
++ put_page(virt_to_head_page(buf));
break;
}
-@@ -436,18 +431,8 @@ static int bgmac_dma_rx_read(struct bgma
- /* Poison the old skb */
- rx->len = cpu_to_le16(0xdead);
- rx->flags = cpu_to_le16(0xbeef);
+ /* 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;
- }
+- 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 +
-@@ -461,6 +446,8 @@ static int bgmac_dma_rx_read(struct bgma
+ BGMAC_RX_BUF_OFFSET + len);
+@@ -465,6 +460,8 @@ static int bgmac_dma_rx_read(struct bgma
handled++;
} while (0);
if (++ring->start >= BGMAC_RX_RING_SLOTS)
ring->start = 0;
+@@ -532,14 +529,14 @@ static void bgmac_dma_rx_ring_free(struc
+
+ 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;
+ }
+ }
+
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