[e1000 2.6 2/11] 82544 PCI-X hang fix + TSO updates

@@ -194,6 +194,7 @@ struct e1000_adapter {
 	uint32_t tx_head_addr;
 	uint32_t tx_fifo_size;
 	atomic_t tx_fifo_stall;
+	boolean_t pcix_82544;
 
 	/* RX */
 	struct e1000_desc_ring rx_ring;

@@ -820,6 +820,12 @@ e1000_configure_tx(struct e1000_adapter 
 		adapter->txd_cmd |= E1000_TXD_CMD_RS;
 	else
 		adapter->txd_cmd |= E1000_TXD_CMD_RPS;
+
+	/* Cache if we're 82544 running in PCI-X because we'll
+	 * need this to apply a workaround later in the send path. */
+	if(adapter->hw.mac_type == e1000_82544 &&
+	   adapter->hw.bus_type == e1000_bus_type_pcix)
+		adapter->pcix_82544 = 1;
 }
 
 /**

@@ -1512,11 +1518,18 @@ e1000_tx_map(struct e1000_adapter *adapt
 {
 	struct e1000_desc_ring *tx_ring = &adapter->tx_ring;
 	struct e1000_buffer *buffer_info;
-	int len = skb->len;
+	unsigned int len = skb->len, max_per_txd = E1000_MAX_DATA_PER_TXD;
 	unsigned int offset = 0, size, count = 0, i;
 
 #ifdef NETIF_F_TSO
-	unsigned int tso = skb_shinfo(skb)->tso_size;
+	unsigned int mss = skb_shinfo(skb)->tso_size;
+	/* The controller does a simple calculation to 
+	 * make sure there is enough room in the FIFO before
+	 * initiating the DMA for each buffer.  The calc is:
+	 * 4 = ceil(buffer len/mss).  To make sure we don't
+	 * overrun the FIFO, adjust the max buffer len if mss
+	 * drops. */
+	if(mss) max_per_txd = min(mss << 2, max_per_txd);
 #endif
 	unsigned int nr_frags = skb_shinfo(skb)->nr_frags;
 	unsigned int f;

@@ -1526,13 +1520,20 @@ e1000_tx_map(struct e1000_adapter *adapt
 
 	while(len) {
 		buffer_info = &tx_ring->buffer_info[i];
-		size = min(len, E1000_MAX_DATA_PER_TXD);
+		size = min(len, max_per_txd);
 #ifdef NETIF_F_TSO
 		/* Workaround for premature desc write-backs
 		 * in TSO mode.  Append 4-byte sentinel desc */
-		if(tso && !nr_frags && size == len && size > 4)
+		if(mss && !nr_frags && size == len && size > 8)
 			size -= 4;
 #endif
+		/* Workaround for potential 82544 hang in PCI-X.  Avoid
+		 * terminating buffers within evenly-aligned dwords. */
+		if(adapter->pcix_82544 &&
+		   !((unsigned long)(skb->data + offset + size - 1) & 4) &&
+		   size > 4)
+			size -= 4;
+
 		buffer_info->length = size;
 		buffer_info->dma =
 			pci_map_single(adapter->pdev,

@@ -1552,22 +1546,30 @@ e1000_tx_map(struct e1000_adapter *adapt
 
 		frag = &skb_shinfo(skb)->frags[f];
 		len = frag->size;
-		offset = 0;
+		offset = frag->page_offset;
 
 		while(len) {
 			buffer_info = &tx_ring->buffer_info[i];
-			size = min(len, E1000_MAX_DATA_PER_TXD);
+			size = min(len, max_per_txd);
 #ifdef NETIF_F_TSO
 			/* Workaround for premature desc write-backs
 			 * in TSO mode.  Append 4-byte sentinel desc */
-			if(tso && f == (nr_frags-1) && size == len && size > 4)
+			if(mss && f == (nr_frags-1) && size == len && size > 8)
 				size -= 4;
 #endif
+			/* Workaround for potential 82544 hang in PCI-X.
+			 * Avoid terminating buffers within evenly-aligned
+			 * dwords. */
+			if(adapter->pcix_82544 &&
+			   !((unsigned long)(frag->page+offset+size-1) & 4) &&
+			   size > 4)
+				size -= 4;
+
 			buffer_info->length = size;
 			buffer_info->dma =
 				pci_map_page(adapter->pdev,
 					frag->page,
-					frag->page_offset + offset,
+					offset,
 					size,
 					PCI_DMA_TODEVICE);
 			buffer_info->time_stamp = jiffies;

@@ -1578,6 +1606,31 @@ e1000_tx_map(struct e1000_adapter *adapt
 			if(++i == tx_ring->count) i = 0;
 		}
 	}
+
+	if(E1000_DESC_UNUSED(&adapter->tx_ring) < count) {
+
+		/* There aren't enough descriptors available to queue up
+		 * this send, so undo the mapping and abort the send. 
+		 * We could have done the check before we mapped the skb,
+		 * but because of all the workarounds (above), it's too
+		 * difficult to predict how many we're going to need.*/
+		i = first;
+
+		while(count--) {
+			buffer_info = &tx_ring->buffer_info[i];
+			if(buffer_info->dma) {
+				pci_unmap_page(adapter->pdev,
+					       buffer_info->dma,
+					       buffer_info->length,
+					       PCI_DMA_TODEVICE);
+				buffer_info->dma = 0;
+			}
+			if(++i == tx_ring->count) i = 0;
+		}
+
+		return 0;
+	}
+
 	i = (i == 0) ? tx_ring->count - 1 : i - 1;
 	tx_ring->buffer_info[i].skb = skb;
 	tx_ring->buffer_info[first].next_to_watch = i;

@@ -1672,29 +1725,19 @@ no_fifo_stall_required:
 	return 0;
 }
 
-/* Tx Descriptors needed, worst case */
-#define TXD_USE_COUNT(S) (((S) >> E1000_MAX_TXD_PWR) + \
-			 (((S) & (E1000_MAX_DATA_PER_TXD - 1)) ? 1 : 0))
-#define DESC_NEEDED TXD_USE_COUNT(MAX_JUMBO_FRAME_SIZE) + \
-	MAX_SKB_FRAGS * TXD_USE_COUNT(PAGE_SIZE) + 1
-
 static int
 e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct e1000_adapter *adapter = netdev->priv;
 	unsigned int first;
 	unsigned int tx_flags = 0;
+	int count;
 
 	if(skb->len <= 0) {
 		dev_kfree_skb_any(skb);
 		return 0;
 	}
 
-	if(E1000_DESC_UNUSED(&adapter->tx_ring) < DESC_NEEDED) {
-		netif_stop_queue(netdev);
-		return 1;
-	}
-
 	if(adapter->hw.mac_type == e1000_82547) {
 		if(e1000_82547_fifo_workaround(adapter, skb)) {
 			netif_stop_queue(netdev);

@@ -1715,7 +1758,12 @@ e1000_xmit_frame(struct sk_buff *skb, st
 	else if(e1000_tx_csum(adapter, skb))
 		tx_flags |= E1000_TX_FLAGS_CSUM;
 
-	e1000_tx_queue(adapter, e1000_tx_map(adapter, skb, first), tx_flags);
+	if((count = e1000_tx_map(adapter, skb, first)))
+		e1000_tx_queue(adapter, count, tx_flags);
+	else {
+		netif_stop_queue(netdev);
+		return 1;
+	}
 
 	netdev->trans_start = jiffies;