From: Feng Tang Date: Fri, 24 Jun 2016 07:26:05 +0000 (+0800) Subject: net: alx: Work around the DMA RX overflow issue X-Git-Tag: firefly_0821_release~176^2~4^2~39^2~21 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=999e0d18786192faf8240a5048dd1a08cf5d4bd0;p=firefly-linux-kernel-4.4.55.git 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 Suggested-by: Eric Dumazet Tested-by: Ole Lukoie Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/net/ethernet/atheros/alx/main.c b/drivers/net/ethernet/atheros/alx/main.c index bd377a6b067d..df54475d163b 100644 --- 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_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);