Re: DSA mv88e6xxx RX frame errors and TCP/IP RX failure

check with ping -s 1500 that packets passed to cpu. mv88e6xxx add
additional dsa tag before the frame so small packets can pass and big
rejected.

also ethtool -S dsaethdevX shows more details stats for Marvell chips.

or opposite, lower mtu on cpu to 1400 and check that ping works. So
from description of patch above it has to work.

Maxim.

2017-08-31 4:46 GMT+03:00 Andrew Lunn [off-list ref]:

quoted

quoted

                       /* Report late collisions as a frame error. */
                        if (status & (BD_ENET_RX_NO | BD_ENET_RX_CL))
                                ndev->stats.rx_frame_errors++;

I don't see anywhere else frame errors are counted, but it would be
good to prove we are looking in the right place.

Andrew,

(adding IMX FEC driver maintainer to CC)

Yes, that's one of them being hit. It looks like ifconfig reports
'frame' as the accumulation of a few stats so here are some more
specifics from /sys/class/net/eth0/statistics:

root@xenial:/sys/devices/soc0/soc/2100000.aips-bus/2188000.ethernet/net/eth0/statistics#
for i in `ls rx_*`; do echo $i:$(cat $i); done
rx_bytes:103229
rx_compressed:0
rx_crc_errors:22
rx_dropped:0
rx_errors:22
rx_fifo_errors:0
rx_frame_errors:22
rx_length_errors:22
rx_missed_errors:0
rx_nohandler:0
rx_over_errors:0
rx_packets:1174
root@xenial:/sys/devices/soc0/soc/2100000.aips-bus/2188000.ethernet/net/eth0/statistics#
ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:D0:12:41:F3:E7
          inet6 addr: fe80::2d0:12ff:fe41:f3e7/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1207 errors:22 dropped:0 overruns:0 frame:66
          TX packets:42 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:106009 (103.5 KiB)  TX bytes:4604 (4.4 KiB)

Instrumenting fec driver I see the following getting hit:

status & BD_ENET_RX_LG /* rx_length_errors: Frame too long */
status & BD_ENET_RX_CR  /* rx_crc_errors: CRC Error */
status & BD_ENET_RX_CL /* rx_frame_errors: Collision? */

Is this a frame size issue where the MV88E6176 is sending frames down
that exceed the MTU because of headers added?

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?

Anyway, try cherry picking that patch and see if it helps.

        Andrew

-- 
Best regards,
Maxim Uvarov