net: fec: unmap the xmit buffer that are not transferred by DMA

[ Upstream commit 178e5f57a8d8f8fc5799a624b96fc31ef9a29ffa ]

The enet IP only support 32 bit, it will use swiotlb buffer to do dma
mapping when xmit buffer DMA memory address is bigger than 4G in i.MX
platform. After stress suspend/resume test, it will print out:

log:
[12826.352864] fec 5b040000.ethernet: swiotlb buffer is full (sz: 191 bytes)
[12826.359676] DMA: Out of SW-IOMMU space for 191 bytes at device 5b040000.ethernet
[12826.367110] fec 5b040000.ethernet eth0: Tx DMA memory map failed

The issue is that the ready xmit buffers that are dma mapped but DMA still
don't copy them into fifo, once MAC restart, these DMA buffers are not unmapped.
So it should check the dma mapping buffer and unmap them.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 3dc2d771a222147c89a3814a34d736e0bcf0d5c4..faf7cdc97ebfc5c638fcb07064a6f6b8229939a7 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -818,6 +818,12 @@ static void fec_enet_bd_init(struct net_device *dev)
                for (i = 0; i < txq->bd.ring_size; i++) {
                        /* Initialize the BD for every fragment in the page. */
                        bdp->cbd_sc = cpu_to_fec16(0);
+                       if (bdp->cbd_bufaddr &&
+                           !IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
+                               dma_unmap_single(&fep->pdev->dev,
+                                                fec32_to_cpu(bdp->cbd_bufaddr),
+                                                fec16_to_cpu(bdp->cbd_datlen),
+                                                DMA_TO_DEVICE);
                        if (txq->tx_skbuff[i]) {
                                dev_kfree_skb_any(txq->tx_skbuff[i]);
                                txq->tx_skbuff[i] = NULL;