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net: alx: Work around the DMA RX overflow issue

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[ Upstream commit 881d0327db37ad917a367c77aff1afa1ee41e0a9 ]

Note: This is a verified backported patch for stable 4.4 kernel, and it
could also be applied to 4.3/4.2/4.1/3.18/3.16

There is a problem with alx devices, that the network link will be
lost in 1-5 minutes after the device is up.

>From debugging without datasheet, we found the error always
happen when the DMA RX address is set to 0x....fc0, which is very
likely to be a HW/silicon problem.

This patch will apply rx skb with 64 bytes longer space, and if the
allocated skb has a 0x...fc0 address, it will use skb_resever(skb, 64)
to advance the address, so that the RX overflow can be avoided.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=70761
Signed-off-by: Feng Tang <feng.tang@intel.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Tested-by: Ole Lukoie <olelukoie@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Feng Tang 2016-06-24 15:26:05 +08:00 committed by Greg Kroah-Hartman
parent 779fb60748
commit 999e0d1878
1 changed files with 6 additions and 1 deletions
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7
drivers/net/ethernet/atheros/alx/main.c
View File

@ -86,9 +86,14 @@ static int alx_refill_rx_ring(struct alx_priv *alx, gfp_t gfp)
while (!cur_buf->skb && next != rxq->read_idx) {
struct alx_rfd *rfd = &rxq->rfd[cur];
skb = __netdev_alloc_skb(alx->dev, alx->rxbuf_size, gfp);
skb = __netdev_alloc_skb(alx->dev, alx->rxbuf_size + 64, gfp);
if (!skb)
break;
/* Workround for the HW RX DMA overflow issue */
if (((unsigned long)skb->data & 0xfff) == 0xfc0)
skb_reserve(skb, 64);
dma = dma_map_single(&alx->hw.pdev->dev,
skb->data, alx->rxbuf_size,
DMA_FROM_DEVICE);