MTU issues.

[Bjørn Mork]

Amol Lad <Amol.Lad at 4rf.com> writes:

> Is similar change needed in cdc_mbim as well?

No, cdc_mbim is very different in this respect.  It decoupled the
rx_urb_size from the netdev mtu from the beginning, since it supports
aggregation in both directions.  The default rx_urb_size is negotiated
by the host and device and should just work without any userspace
intervention. 

The cdc_mbim/cdc_ncm driver also allows overriding the defaults by tuning

 /sys/class/net/<iface>/cdc_ncm/rx_max
 /sys/class/net/<iface>/cdc_ncm/tx_max

See https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-net-cdc_ncm

We could do a similar thing for qmi_wwan, like Daniele suggested, But I
am not convinced it is needed.  And I beleive we should try to set a
working default in any case, which implies that we have to increase the
rx_urb_size when we configure muxing.


Bjørn