quoted

I did fix an issue recently with that. See

commit fbbeefdd21049fcf9437c809da3828b210577f36
Author: Andrew Lunn [off-list ref]
Date:   Sun Jul 30 19:36:05 2017 +0200

    net: fec: Allow reception of frames bigger than 1522 bytes

    The FEC Receive Control Register has a 14 bit field indicating the
    longest frame that may be received. It is being set to 1522. Frames
    longer than this are discarded, but counted as being in error.

    When using DSA, frames from the switch has an additional header,
    either 4 or 8 bytes if a Marvell switch is used. Thus a full MTU frame
    of 1522 bytes received by the switch on a port becomes 1530 bytes when
    passed to the host via the FEC interface.

    Change the maximum receive size to 2048 - 64, where 64 is the maximum
    rx_alignment applied on the receive buffer for AVB capable FEC
    cores. Use this value also for the maximum receive buffer size. The
    driver is already allocating a receive SKB of 2048 bytes, so this
    change should not have any significant effects.

    Tested on imx51, imx6, vf610.

    Signed-off-by: Andrew Lunn [off-list ref]
    Signed-off-by: David S. Miller [off-list ref]


However, this is was of an all/nothing problem. All frames with the
full MTU were getting dropped, where as i think you are only seeing a
few dropped?

Andrew,

Indeed this does resolve the issue. I see a burst of FIFO overruns
initially when receiving an iperf bandwidth test but that would be
caused by the IMX6 errata and should be mitigated via pause frames.
After that short burst I see no other errors and iperf works fine.

Should we get this patch in the linux-stable tree for the 4.9 kernel?

Hi David

Please could you add

fbbeefdd2104 ("net: fec: Allow reception of frames bigger than 1522 bytes")

to stable.

Thanks
	Andrew