Bug in drivers/net/ethernet/freescale/fec_main.c, TX is broken. In 4.0.0-rc3

[Панов Андрей]

Hello!
Adding lakml to cc:

> Commit 2b995f63987013bacde99168218f9c7b252bdcf1 in 4.0.0-rc3 introduces a nasty bug in transmit, corrupting packets.
>
> To reproduce:
>
> $ dd if=/dev/zero of=zeros bs=1M count=20
> $ md5sum -b zeros
> 8f4e33f3dc3e414ff94e5fb6905cba8c *zeros
>
> This checksum is correct.
>
> Copy file "zeros" to another host with NFS, and it gets corrupted, checksum is changed.
> File should be big, small amounts of transmit isn't affected.
>
> I use an i.MX6 Quad board.
>
> If this commit is reverted, all works fine.

3.19 works fine too.
And it is not random corruption, when copying all-zero file this is received on NFS host:
$ hd zeros | head -16
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
0052c0f0  00 00 00 00 00 00 00 00  1c f0 9f e5 1c f0 9f e5  |................|
0052c100  1c f0 9f e5 1c f0 9f e5  1c f0 9f e5 1c f0 9f e5  |................|
0052c110  1c f0 9f e5 1c f0 9f e5  1c f0 9f e5 74 fb 00 00  |............t...|
0052c120  bc ff 93 00 c0 ff 93 00  c4 ff 93 00 c8 ff 93 00  |................|
0052c130  cc ff 93 00 d0 ff 93 00  d4 ff 93 00 d8 ff 93 00  |................|
0052c140  13 00 00 00 28 63 29 20  43 6f 70 79 72 69 67 68  |....(c) Copyrigh|
0052c150  74 20 32 30 30 37 2d 32  30 31 32 2c 20 46 72 65  |t 2007-2012, Fre|
0052c160  65 73 63 61 6c 65 20 53  65 6d 69 63 6f 6e 64 75  |escale Semicondu|
0052c170  63 74 6f 72 2e 20 41 6c  6c 20 72 69 67 68 74 73  |ctor. All rights|
0052c180  20 72 65 73 65 72 76 65  64 2e 00 00 dd 00 2c 41  | reserved.....,A|
0052c190  11 73 00 00 d3 74 00 00  3d 75 00 00 a9 78 00 00  |.s...t..=u...x..|
0052c1a0  4f 78 00 00 75 77 00 00  07 76 00 00 c3 79 00 00  |Ox..uw...v...y..|
0052c1b0  09 7a 00 00 75 7a 00 00  97 22 00 00 49 1f 00 00  |.z..uz..."..I...|
0052c1c0  b9 21 00 00 ff 70 00 00  90 21 90 00 23 4a 52 f8  |.!...p...!..#JR.|

Looks like zero page with vectors at beginning.
Freescale i.MX6 Quad-based Embedsky E9 board.

--
 Андрей