[PATCHv4 net-next 01/13] net: mvpp2: fix DMA address calculation in mvpp2_txq_inc_put()

[Thomas Petazzoni]

When TX descriptors are filled in, the buffer DMA address is split
between the tx_desc->buf_phys_addr field (high-order bits) and
tx_desc->packet_offset field (5 low-order bits).

However, when we re-calculate the DMA address from the TX descriptor in
mvpp2_txq_inc_put(), we do not take tx_desc->packet_offset into
account. This means that when the DMA address is not aligned on a 32
bytes boundary, we end up calling dma_unmap_single() with a DMA address
that was not the one returned by dma_map_single().

This inconsistency is detected by the kernel when DMA_API_DEBUG is
enabled. We fix this problem by properly calculating the DMA address in
mvpp2_txq_inc_put().

Cc: <sta...@vger.kernel.org>
Signed-off-by: Thomas Petazzoni <thomas.petazz...@free-electrons.com>
---
 drivers/net/ethernet/marvell/mvpp2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2.c 
b/drivers/net/ethernet/marvell/mvpp2.c
index 4fe430c..5f1f23e 100644
--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -991,7 +991,7 @@ static void mvpp2_txq_inc_put(struct mvpp2_txq_pcpu 
*txq_pcpu,
                txq_pcpu->buffs + txq_pcpu->txq_put_index;
        tx_buf->skb = skb;
        tx_buf->size = tx_desc->data_size;
-       tx_buf->phys = tx_desc->buf_phys_addr;
+       tx_buf->phys = tx_desc->buf_phys_addr + tx_desc->packet_offset;
        txq_pcpu->txq_put_index++;
        if (txq_pcpu->txq_put_index == txq_pcpu->size)
                txq_pcpu->txq_put_index = 0;
-- 
2.7.4