[PATCH net-drivers-2.6 5/11] ixgb: Reset status in the Rx descriptor prior to handing it to the controller

["Chilakala, Mallikarjuna" <mallikarjuna.chilakala@xxxxxxxxx>]

Reset status in the Rx descriptor prior to handing it to the controller.
Leave three Rx descriptors unused

Signed-off-by: Mallikarjuna R Chilakala
<mallikarjuna.chilakala@xxxxxxxxx>
Signed-off-by: Ganesh Venkatesan <ganesh.venkatesan@xxxxxxxxx>
Signed-off-by: John Ronciak <john.ronciak@xxxxxxxxx>
diff -up net-drivers-2.6/drivers/net/ixgb/ixgb_main.c
net-drivers-2.6/drivers/net/ixgb.new/ixgb_main.c
--- net-drivers-2.6/drivers/net/ixgb/ixgb_main.c        2005-04-05
23:06:36.332229456 -0700
+++ net-drivers-2.6/drivers/net/ixgb.new/ixgb_main.c    2005-04-05
23:06:38.283932752 -0700
@@ -1977,8 +1977,8 @@ ixgb_alloc_rx_buffers(struct ixgb_adapte

        num_group_tail_writes = IXGB_RX_BUFFER_WRITE;

-       /* leave one descriptor unused */
-       while(--cleancount > 0) {
+       /* leave three descriptors unused */
+       while(--cleancount > 2) {
                rx_desc = IXGB_RX_DESC(*rx_ring, i);

                skb = dev_alloc_skb(adapter->rx_buffer_len +
NET_IP_ALIGN);
@@ -2005,6 +1933,10 @@ ixgb_alloc_rx_buffers(struct ixgb_adapte
                                   PCI_DMA_FROMDEVICE);

                rx_desc->buff_addr = cpu_to_le64(buffer_info->dma);
+               /* guarantee DD bit not set now before h/w gets
descriptor
+                * this is the rest of the workaround for h/w double
+                * writeback. */
+               rx_desc->status = 0;

                if((i & ~(num_group_tail_writes- 1)) == i) {
                        /* Force memory writes to complete before
letting h/w