netdev - [PATCH 0/3] net: fec: updates to align IP header

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Message-Id: <1474728139-9335-1-git-send-email-eric@nelint.com>
Date:   Sat, 24 Sep 2016 07:42:16 -0700
From:   Eric Nelson <eric@...int.com>
To:     netdev@...r.kernel.org
Cc:     linux@....linux.org.uk, andrew@...n.ch, fugang.duan@....com,
        otavio@...ystems.com.br, edumazet@...gle.com,
        troy.kisky@...ndarydevices.com, davem@...emloft.net,
        u.kleine-koenig@...gutronix.de, Eric Nelson <eric@...int.com>
Subject: [PATCH 0/3] net: fec: updates to align IP header

This patch series is the outcome of investigation into very high
numbers of alignment faults on kernel 4.1.33 from the linux-fslc
tree:
    https://github.com/freescale/linux-fslc/tree/4.1-1.0.x-imx

The first two patches remove support for the receive accelerator (RACC) from
the i.MX25 and i.MX27 SoCs which don't support the function.

The third patch enables hardware alignment of the ethernet packet payload
(and especially the IP header) to prevent alignment faults in the IP stack.

Testing on i.MX6UL on the 4.1.33 kernel showed that this patch removed
on the order of 70k alignment faults during a 100MiB transfer using 
wget.

Testing on an i.MX6Q (SABRE Lite) board on net-next (4.8.0-rc7) showed
a much more modest improvement from 10's of faults, and it's not clear
why that's the case.

Eric Nelson (3):
  net: fec: remove QUIRK_HAS_RACC from i.mx25
  net: fec: remove QUIRK_HAS_RACC from i.mx27
  net: fec: align IP header in hardware

 drivers/net/ethernet/freescale/fec_main.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

-- 
2.7.4