Thank you Bjorn for the help and suggestions. These are parameters that the driver ends up choosing: /sys/class/net/wwan0/cdc_ncm/bmNtbFormatsSupported:0x0003 /sys/class/net/wwan0/cdc_ncm/dwNtbInMaxSize:131072 /sys/class/net/wwan0/cdc_ncm/dwNtbOutMaxSize:16384 /sys/class/net/wwan0/cdc_ncm/min_tx_pkt:14848 /sys/class/net/wwan0/cdc_ncm/rx_max:16384 /sys/class/net/wwan0/cdc_ncm/tx_max:16384 /sys/class/net/wwan0/cdc_ncm/tx_timer_usecs:400 /sys/class/net/wwan0/cdc_ncm/wNdpInAlignment:4 /sys/class/net/wwan0/cdc_ncm/wNdpInDivisor:4 /sys/class/net/wwan0/cdc_ncm/wNdpInPayloadRemainder:2 /sys/class/net/wwan0/cdc_ncm/wNdpOutAlignment:4 /sys/class/net/wwan0/cdc_ncm/wNdpOutDivisor:4 /sys/class/net/wwan0/cdc_ncm/wNdpOutPayloadRemainder:2 /sys/class/net/wwan0/cdc_ncm/wNtbOutMaxDatagrams:0 Sorry if I did not report them before. If I missed someone in CC please add it guys. Kevin - after you discovered that the device might handle the offset in a different way, have you tried this approach? On Thu, 27 Nov 2014, Bjørn Mork wrote: ==Date: Thu, 27 Nov 2014 11:03:24 ==From: Bjørn Mork <bjorn@xxxxxxx> ==To: Enrico Mioso <mrkiko.rs@xxxxxxxxx> ==Cc: youtux@xxxxxxxxx, alexxst@xxxxxxxxx, linux-usb@xxxxxxxxxxxxxxx, == netdev@xxxxxxxxxxxxxxx ==Subject: Re: Is this 32-bit NCM? == ==Enrico Mioso <mrkiko.rs@xxxxxxxxx> writes: == ==> Ok - we can arrive to some ocnclusions regarding the E3272. ==> First of all - the modem seems buggy enough to not be able to handle requests ==> for different formats. You need to unplug and re-plug it, but this is onlyan ==> impression and is reasonable. ==> ==> Then - the modem will accept to ndisdup the connection with ==> at^ndisdup=1,1,"internet" ==> but - if we use huawei_cdc_ncm + cdc_ncm we have no flow handling messages and ==> the modem stops here. ==> If we use the cdc_ncm 32-bit driver (modified) we get lotfs of ==> ^dsflorpt ==> that's how it should be. ==> So I think we can say that something is changing. ==> Then there's the alignment problem you mentioned in your previous reply. And ==> this is hard to solve. ==> could you try to help me understand where the problem is? ==> I feel like we are very close to the solution but something isn't working. ==> Or might be just try to change the 16 bit driver? == ==If you use a recent version of the driver as a basis, then you get the ==CDC NCM NTB parameters in sysfs (if not, then you need to enable ==debugging and look in the log for these values). For example: == ==bjorn@nemi:~$ grep . /sys/class/net/wwan0/cdc_ncm/* ==/sys/class/net/wwan0/cdc_ncm/bmNtbFormatsSupported:0x0001 ==/sys/class/net/wwan0/cdc_ncm/dwNtbInMaxSize:15360 ==/sys/class/net/wwan0/cdc_ncm/dwNtbOutMaxSize:15360 ==/sys/class/net/wwan0/cdc_ncm/min_tx_pkt:13824 ==/sys/class/net/wwan0/cdc_ncm/rx_max:15360 ==/sys/class/net/wwan0/cdc_ncm/tx_max:15360 ==/sys/class/net/wwan0/cdc_ncm/tx_timer_usecs:400 ==/sys/class/net/wwan0/cdc_ncm/wNdpInAlignment:4 ==/sys/class/net/wwan0/cdc_ncm/wNdpInDivisor:1 ==/sys/class/net/wwan0/cdc_ncm/wNdpInPayloadRemainder:0 ==/sys/class/net/wwan0/cdc_ncm/wNdpOutAlignment:4 ==/sys/class/net/wwan0/cdc_ncm/wNdpOutDivisor:32 ==/sys/class/net/wwan0/cdc_ncm/wNdpOutPayloadRemainder:0 ==/sys/class/net/wwan0/cdc_ncm/wNtbOutMaxDatagrams:32 == == ==The possible problem I am thinking of is proper handling of the ==wNdp*PayloadRemainder values. See section 3.3.4 "NCM Ethernet Frame ==Alignment" in the spec. Which is confusing as hell, but if I understand ==it correctly then we are supposed to align the start of the IP packets ==(the "payload", _not_ the ethernet frame) to a whole wNdp*Divisor number ==as long as the wNdp*PayloadRemainder is 0. == == ==Bjørn ==
