Hi,
I'm struggling with Telit LE922 modem that presents an MBIM device.
The modem works fine in Windows, while in Linux (tested with 4.9 rc1)
data connection is not functional: using ifconfig I can see
wwp0s20u8i2 Link encap:Ethernet HWaddr e6:c0:3b:97:80:de
inet addr:176.246.94.9 Bcast:176.246.94.11 Mask:255.255.255.252
UP BROADCAST RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:15 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:40 (40.0 B)
so the issue seems to be in tx.
I'm using an USB hw sniffer for trying to understand the problem; this
is an example of a NCM packet with Windows 10 driver:
4E 43 4D 48 0C 00 0B 02 48 00 38 00 45 00 00 28
78 E8 40 00 80 06 63 68 05 5C 7A E5 D8 3A C6 03
E9 08 01 BB FB 36 F0 EA C6 8C D8 CB 50 10 80 00
9B 16 00 00 00 00 00 00 49 50 53 00 10 00 00 00
0C 00 28 00 00 00 00 00
16 bit NTB, with NDP at the end. So I enabled CDC_NCM_FLAG_NDP_TO_END,
but still the device is not properly working.
This is the first properly transmitted acked packet in Linux:
4E 43 4D 48 0C 00 00 00 80 00 34 00 46 C0 00 28
00 00 40 00 01 02 F4 F9 B0 F6 5E 09 E0 00 00 16
94 04 00 00 22 00 F9 02 00 00 00 01 04 00 00 00
E0 00 00 FB 49 50 53 00 10 00 00 00 0C 00 28 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
that looks like quite similar than the Windows one (besides the final padding).
Then all the following out packets are nacked, e.g:
4E 43 4D 48 0C 00 01 00 D8 00 8C 00 45 00 00 3E
05 71 40 00 40 11 0C E8 B0 F6 5E 09 0A 85 0E D2
B3 30 00 35 00 2A D3 57 58 6A 01 00 00 01 00 00
00 00 00 00 05 64 61 69 73 79 06 75 62 75 6E 74
75 03 63 6F 6D 00 00 01 00 01 00 00 45 00 00 3E
2A EC 40 00 40 11 91 8A B0 F6 5E 09 0A 84 64 B5
B3 30 00 35 00 2A 7D 75 58 6A 01 00 00 01 00 00
00 00 00 00 05 64 61 69 73 79 06 75 62 75 6E 74
75 03 63 6F 6D 00 00 01 00 01 00 00 49 50 53 00
14 00 00 00 0C 00 3E 00 4C 00 3E 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
Those packets look good to me: the main difference with Windows is the
presence of more than one datagram, but, as far as I understand, this
should not be a problem since the modem reports:
dwNtbInMaxSize=16384 dwNtbOutMaxSize=16384 wNdpOutPayloadRemainder=0
wNdpOutDivisor=4 wNdpOutAlignment=4 wNtbOutMaxDatagrams=16 flags=0x20
while in Windows it seems that always only one datagram is sent.
My thought is that the problem is in the modem firmware: in some way,
the first acked packet is breaking things inside the modem that is not
able to receive packets anymore, but maybe there is some other
problems in the tx packets created by the driver and I'm not able to
catch it.
Does someone have an hint about this?
Is there a way to configure the cdc_mbim driver in order to have
exactly the same packet format sent in Windows?
USB traces taken with TotalPhase Datacenter are available at
https://drive.google.com/open?id=0B1kPnH2g8ISIZWJiV05qeWN5dVE
Thanks,
Daniele
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