| From: Feng Tang <feng.tang@intel.com> |
| Date: Fri, 24 Jun 2016 15:26:05 +0800 |
| Subject: net: alx: Work around the DMA RX overflow issue |
| |
| [ 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: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| drivers/net/ethernet/atheros/alx/main.c | 7 ++++++- |
| 1 file changed, 6 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/net/ethernet/atheros/alx/main.c |
| +++ b/drivers/net/ethernet/atheros/alx/main.c |
| @@ -86,9 +86,14 @@ static int alx_refill_rx_ring(struct alx |
| 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); |
