On Wed, Aug 30, 2017 at 3:06 PM, Andrew Lunn [off-list ref] wrote:

On Wed, Aug 30, 2017 at 12:53:56PM -0700, Tim Harvey wrote:

quoted

Greetings,

I'm seeing RX frame errors when using the mv88e6xxx DSA driver on
4.13-rc7. The board I'm using is a GW5904 [1] which has an IMX6 FEC
MAC (eth0) connected via RGMII to a MV88E6176 with its downstream
P0/P1/P2/P3 to front panel RJ45's (lan1-lan4).

Hi Tim

Can you confirm the counter is this one:

                       /* 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?

Tim