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authorEric Nelson <eric@nelint.com>2016-09-24 07:42:19 -0700
committerDavid S. Miller <davem@davemloft.net>2016-09-27 07:39:34 -0400
commit3ac72b7b63d57b231dda1e8f8d13872e0d7e8603 (patch)
treedaf1ca189ea3eb820b243e1752a6be19bdbdfbfb /drivers
parent97dc499c1ae396bc0d529f5b1aef3138de1ae7de (diff)
downloadlinux-3ac72b7b63d57b231dda1e8f8d13872e0d7e8603.tar.bz2
net: fec: align IP header in hardware
The FEC receive accelerator (RACC) supports shifting the data payload of received packets by 16-bits, which aligns the payload (IP header) on a 4-byte boundary, which is, if not required, at least strongly suggested by the Linux networking layer. Without this patch, a huge number of alignment faults will be taken by the IP stack, as seen in /proc/cpu/alignment: ~/$ cat /proc/cpu/alignment User: 0 System: 72645 (inet_gro_receive+0x104/0x27c) Skipped: 0 Half: 0 Word: 0 DWord: 0 Multi: 72645 User faults: 3 (fixup+warn) This patch was suggested by Andrew Lunn in this message to linux-netdev: http://marc.info/?l=linux-arm-kernel&m=147465452108384&w=2 and adapted from a patch by Russell King from 2014: http://git.arm.linux.org.uk/cgit/linux-arm.git/commit/?id=70d8a8a Signed-off-by: Eric Nelson <eric@nelint.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/ethernet/freescale/fec_main.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 3fb11f929adc..692ee248e486 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -180,6 +180,7 @@ MODULE_PARM_DESC(macaddr, "FEC Ethernet MAC address");
/* FEC receive acceleration */
#define FEC_RACC_IPDIS (1 << 1)
#define FEC_RACC_PRODIS (1 << 2)
+#define FEC_RACC_SHIFT16 BIT(7)
#define FEC_RACC_OPTIONS (FEC_RACC_IPDIS | FEC_RACC_PRODIS)
/*
@@ -945,9 +946,11 @@ fec_restart(struct net_device *ndev)
#if !defined(CONFIG_M5272)
if (fep->quirks & FEC_QUIRK_HAS_RACC) {
- /* set RX checksum */
val = readl(fep->hwp + FEC_RACC);
+ /* align IP header */
+ val |= FEC_RACC_SHIFT16;
if (fep->csum_flags & FLAG_RX_CSUM_ENABLED)
+ /* set RX checksum */
val |= FEC_RACC_OPTIONS;
else
val &= ~FEC_RACC_OPTIONS;
@@ -1428,6 +1431,12 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
prefetch(skb->data - NET_IP_ALIGN);
skb_put(skb, pkt_len - 4);
data = skb->data;
+
+#if !defined(CONFIG_M5272)
+ if (fep->quirks & FEC_QUIRK_HAS_RACC)
+ data = skb_pull_inline(skb, 2);
+#endif
+
if (!is_copybreak && need_swap)
swap_buffer(data, pkt_len);