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.cavall...@st.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |   67 ++++++++++++++++-----
 1 files changed, 52 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c 
b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 6b83213..d68775a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -98,6 +98,10 @@ static int buf_sz = DEFAULT_BUFSIZE;
 module_param(buf_sz, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(buf_sz, "DMA buffer size");
 
+static int minrx = 256;
+module_param(minrx, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(minrx, "Copy only tiny-frames");
+
 static const u32 default_msg_level = (NETIF_MSG_DRV | NETIF_MSG_PROBE |
                                      NETIF_MSG_LINK | NETIF_MSG_IFUP |
                                      NETIF_MSG_IFDOWN | NETIF_MSG_TIMER);
@@ -147,6 +151,8 @@ static void stmmac_verify_args(void)
                pause = PAUSE_TIME;
        if (eee_timer < 0)
                eee_timer = STMMAC_DEFAULT_LPI_TIMER;
+       if (minrx < 0)
+               minrx = ETH_FRAME_LEN;
 }
 
 /**
@@ -2198,8 +2204,7 @@ static inline void stmmac_rx_refill(struct stmmac_priv 
*priv)
                        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;
@@ -2322,23 +2327,52 @@ static int stmmac_rx(struct stmmac_priv *priv, int 
limit)
                                        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 < minrx)) {
+                               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);
@@ -3235,6 +3269,9 @@ static int __init stmmac_cmdline_opt(char *str)
                } else if (!strncmp(opt, "chain_mode:", 11)) {
                        if (kstrtoint(opt + 11, 0, &chain_mode))
                                goto err;
+               } else if (!strncmp(opt, "minrx:", 6)) {
+                       if (kstrtoint(opt + 6, 0, &minrx))
+                               goto err;
                }
        }
        return 0;
-- 
1.7.4.4

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