3G modem and USB, old & new

I tried using my 3g modem (Huawei E196) yesterday, with both the
old and the new USB stack, and it fails in slightly different
ways.

With the old USB stack, it works until I actually try to get a packet
of more than approx 1024 bytes through, at which point it hangs with
	ucom0: ucomreadcb: IOERROR
And I need to stop and start ppp(1) to get it working until the next
big packet comes around.

It does not help to reduce the MRU because two small packets back to
back will also trigger this error.

With the new USB stack, I am not able to talk to the modem at all
using the cuaU* devices.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.