stmmac: do not perform zero-copy for rx frames
This patch is to allow this driver to copy tiny frames during the reception
process. This is giving more stability while stressing the driver on STi
embedded systems.
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 3cc1355..2ffe8dd 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -91,6 +91,8 @@
module_param(buf_sz, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(buf_sz, "DMA buffer size");
+#define STMMAC_RX_COPYBREAK 256
+
static const u32 default_msg_level = (NETIF_MSG_DRV | NETIF_MSG_PROBE |
NETIF_MSG_LINK | NETIF_MSG_IFUP |
NETIF_MSG_IFDOWN | NETIF_MSG_TIMER);
@@ -1808,6 +1810,7 @@
priv->xstats.threshold = tc;
priv->dma_buf_sz = STMMAC_ALIGN(buf_sz);
+ priv->rx_copybreak = STMMAC_RX_COPYBREAK;
ret = alloc_dma_desc_resources(priv);
if (ret < 0) {
@@ -2159,8 +2162,7 @@
struct sk_buff *skb;
skb = netdev_alloc_skb_ip_align(priv->dev, bfsize);
-
- if (unlikely(skb == NULL))
+ if (unlikely(!skb))
break;
priv->rx_skbuff[entry] = skb;
@@ -2282,23 +2284,52 @@
pr_debug("\tframe size %d, COE: %d\n",
frame_len, status);
}
- skb = priv->rx_skbuff[entry];
- if (unlikely(!skb)) {
- pr_err("%s: Inconsistent Rx descriptor chain\n",
- priv->dev->name);
- priv->dev->stats.rx_dropped++;
- break;
+
+ if (unlikely(frame_len < priv->rx_copybreak)) {
+ skb = netdev_alloc_skb_ip_align(priv->dev,
+ frame_len);
+ if (unlikely(!skb)) {
+ if (net_ratelimit())
+ dev_warn(priv->device,
+ "packet dropped\n");
+ priv->dev->stats.rx_dropped++;
+ break;
+ }
+
+ dma_sync_single_for_cpu(priv->device,
+ priv->rx_skbuff_dma
+ [entry], frame_len,
+ DMA_FROM_DEVICE);
+ skb_copy_to_linear_data(skb,
+ priv->
+ rx_skbuff[entry]->data,
+ frame_len);
+
+ skb_put(skb, frame_len);
+ dma_sync_single_for_device(priv->device,
+ priv->rx_skbuff_dma
+ [entry], frame_len,
+ DMA_FROM_DEVICE);
+ } else {
+ skb = priv->rx_skbuff[entry];
+ if (unlikely(!skb)) {
+ pr_err("%s: Inconsistent Rx chain\n",
+ priv->dev->name);
+ priv->dev->stats.rx_dropped++;
+ break;
+ }
+ prefetch(skb->data - NET_IP_ALIGN);
+ priv->rx_skbuff[entry] = NULL;
+
+ skb_put(skb, frame_len);
+ dma_unmap_single(priv->device,
+ priv->rx_skbuff_dma[entry],
+ priv->dma_buf_sz,
+ DMA_FROM_DEVICE);
}
- prefetch(skb->data - NET_IP_ALIGN);
- priv->rx_skbuff[entry] = NULL;
stmmac_get_rx_hwtstamp(priv, entry, skb);
- skb_put(skb, frame_len);
- dma_unmap_single(priv->device,
- priv->rx_skbuff_dma[entry],
- priv->dma_buf_sz, DMA_FROM_DEVICE);
-
if (netif_msg_pktdata(priv)) {
pr_debug("frame received (%dbytes)", frame_len);
print_pkt(skb->data, frame_len);