octeon_ep: fix tx dma unmap len values in SG

Lengths of SG pointers are kept in the following order in
the SG entries in hardware.
 63      48|47     32|31     16|15       0
 -----------------------------------------
 |  Len 0  |  Len 1  |  Len 2  |  Len 3  |
 -----------------------------------------
 |                Ptr 0                  |
 -----------------------------------------
 |                Ptr 1                  |
 -----------------------------------------
 |                Ptr 2                  |
 -----------------------------------------
 |                Ptr 3                  |
 -----------------------------------------
Dma pointers have to be unmapped based on their
respective lengths given in this format.

Fixes: 37d79d0 ("octeon_ep: add Tx/Rx processing and interrupt support")
Signed-off-by: Shinas Rasheed <srasheed@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: shinas-marvell

drivers/net/ethernet/marvell/octeon_ep/octep_main.c

@@ -734,13 +734,13 @@ static netdev_tx_t octep_start_xmit(struct sk_buff *skb,
 dma_map_sg_err:
 	if (si > 0) {
 		dma_unmap_single(iq->dev, sglist[0].dma_ptr[0],
-				 sglist[0].len[0], DMA_TO_DEVICE);
-		sglist[0].len[0] = 0;
+				 sglist[0].len[3], DMA_TO_DEVICE);
+		sglist[0].len[3] = 0;
 	}
 	while (si > 1) {
 		dma_unmap_page(iq->dev, sglist[si >> 2].dma_ptr[si & 3],
-			       sglist[si >> 2].len[si & 3], DMA_TO_DEVICE);
-		sglist[si >> 2].len[si & 3] = 0;
+			       sglist[si >> 2].len[3 - (si & 3)], DMA_TO_DEVICE);
+		sglist[si >> 2].len[3 - (si & 3)] = 0;
 		si--;
 	}
 	tx_buffer->gather = 0;

drivers/net/ethernet/marvell/octeon_ep/octep_tx.c

@@ -69,12 +69,12 @@ int octep_iq_process_completions(struct octep_iq *iq, u16 budget)
 		compl_sg++;
 
 		dma_unmap_single(iq->dev, tx_buffer->sglist[0].dma_ptr[0],
-				 tx_buffer->sglist[0].len[0], DMA_TO_DEVICE);
+				 tx_buffer->sglist[0].len[3], DMA_TO_DEVICE);
 
 		i = 1; /* entry 0 is main skb, unmapped above */
 		while (frags--) {
 			dma_unmap_page(iq->dev, tx_buffer->sglist[i >> 2].dma_ptr[i & 3],
-				       tx_buffer->sglist[i >> 2].len[i & 3], DMA_TO_DEVICE);
+				       tx_buffer->sglist[i >> 2].len[3 - (i & 3)], DMA_TO_DEVICE);
 			i++;
 		}
 
@@ -131,13 +131,13 @@ static void octep_iq_free_pending(struct octep_iq *iq)
 
 		dma_unmap_single(iq->dev,
 				 tx_buffer->sglist[0].dma_ptr[0],
-				 tx_buffer->sglist[0].len[0],
+				 tx_buffer->sglist[0].len[3],
 				 DMA_TO_DEVICE);
 
 		i = 1; /* entry 0 is main skb, unmapped above */
 		while (frags--) {
 			dma_unmap_page(iq->dev, tx_buffer->sglist[i >> 2].dma_ptr[i & 3],
-				       tx_buffer->sglist[i >> 2].len[i & 3], DMA_TO_DEVICE);
+				       tx_buffer->sglist[i >> 2].len[3 - (i & 3)], DMA_TO_DEVICE);
 			i++;
 		}
 

drivers/net/ethernet/marvell/octeon_ep/octep_tx.h

@@ -17,7 +17,21 @@
 #define TX_BUFTYPE_NET_SG        2
 #define NUM_TX_BUFTYPES          3
 
-/* Hardware format for Scatter/Gather list */
+/* Hardware format for Scatter/Gather list
+ *
+ * 63      48|47     32|31     16|15       0
+ * -----------------------------------------
+ * |  Len 0  |  Len 1  |  Len 2  |  Len 3  |
+ * -----------------------------------------
+ * |                Ptr 0                  |
+ * -----------------------------------------
+ * |                Ptr 1                  |
+ * -----------------------------------------
+ * |                Ptr 2                  |
+ * -----------------------------------------
+ * |                Ptr 3                  |
+ * -----------------------------------------
+ */
 struct octep_tx_sglist_desc {
 	u16 len[4];
 	dma_addr_t dma_ptr[4];