Patch "net: fec: unmap the xmit buffer that are not transferred by DMA" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
net-fec-unmap-the-xmit-buffer-that-are-not-transferred-by-dma.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Fugang Duan <[email protected]>
Date: Fri, 22 Dec 2017 17:12:09 +0800
Subject: net: fec: unmap the xmit buffer that are not transferred by DMA

From: Fugang Duan <[email protected]>

[ 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.

---
 drivers/net/ethernet/freescale/fec_main.c |    6 ++++++
 1 file changed, 6 insertions(+)

@@ -818,6 +818,12 @@ static void fec_enet_bd_init(struct net_
 		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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/net-fec-unmap-the-xmit-buffer-that-are-not-transferred-by-dma.patch