1 files changed, 24 insertions, 5 deletions

diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
index 60f96c468a24..67d414b061d7 100644
--- a/drivers/net/r8169.c
+++ b/drivers/net/r8169.c
@@ -186,7 +186,12 @@ static struct pci_device_id rtl8169_pci_tbl[] = {
 
 MODULE_DEVICE_TABLE(pci, rtl8169_pci_tbl);
 
-static int rx_copybreak = 200;
+/*
+ * we set our copybreak very high so that we don't have
+ * to allocate 16k frames all the time (see note in
+ * rtl8169_open()
+ */
+static int rx_copybreak = 16383;
 static int use_dac;
 static struct {
         u32 msg_enable;
@@ -3245,9 +3250,13 @@ static void __devexit rtl8169_remove_one(struct pci_dev *pdev)
 }
 
 static void rtl8169_set_rxbufsize(struct rtl8169_private *tp,
-                                  struct net_device *dev)
+                                  unsigned int mtu)
 {
-        unsigned int max_frame = dev->mtu + VLAN_ETH_HLEN + ETH_FCS_LEN;
+        unsigned int max_frame = mtu + VLAN_ETH_HLEN + ETH_FCS_LEN;
+
+        if (max_frame != 16383)
+                printk(KERN_WARNING "WARNING! Changing of MTU on this NIC"
+                        "May lead to frame reception errors!\n");
 
         tp->rx_buf_sz = (max_frame > RX_BUF_SIZE) ? max_frame : RX_BUF_SIZE;
 }
@@ -3259,7 +3268,17 @@ static int rtl8169_open(struct net_device *dev)
         int retval = -ENOMEM;
 
 
-        rtl8169_set_rxbufsize(tp, dev);
+        /*
+         * Note that we use a magic value here, its wierd I know
+         * its done because, some subset of rtl8169 hardware suffers from
+         * a problem in which frames received that are longer than
+         * the size set in RxMaxSize register return garbage sizes
+         * when received.  To avoid this we need to turn off filtering,
+         * which is done by setting a value of 16383 in the RxMaxSize register
+         * and allocating 16k frames to handle the largest possible rx value
+         * thats what the magic math below does.
+         */
+        rtl8169_set_rxbufsize(tp, 16383 - VLAN_ETH_HLEN - ETH_FCS_LEN);
 
         /*
          * Rx and Tx desscriptors needs 256 bytes alignment.
@@ -3912,7 +3931,7 @@ static int rtl8169_change_mtu(struct net_device *dev, int new_mtu)
 
         rtl8169_down(dev);
 
-        rtl8169_set_rxbufsize(tp, dev);
+        rtl8169_set_rxbufsize(tp, dev->mtu);
 
         ret = rtl8169_init_ring(dev);
         if (ret < 0)