On Fri, Oct 3, 2014 at 10:01 AM, Erik Alapää <erik.alapaa@xxxxxxxxx> wrote: > Problem: When connecting to a Huawei E3276 LTE modem using > 'AT+CGACT=1,1' in minicom over /dev/cdc-wdm1, the cdc-wdm device > freezes for 3-5 minutes until accepting AT commands again. > > Keywords: huawei_cdc_ncm, LTE, AT commands, cdc-wdm > > Detailed problem description: > > I am using a 4G mobile USB dongle with the huawei_cdc_ncm driver in > Linux kernel 3.16. In general, the driver works well, but one major > issue is that bringing the modem up using 'AT+CGACT=1.1' freezes the > /dev/cdc-wdm1 control device for 3-5 minutes. After that, the device > accepts more commands over minicom. Note that I do get connectivity, > directly after the CGACT I can get a DHCP address for wwan0 and the > bandwidth is approx 20 Mbit/s downstream and 6 Mbit/s upstream. > > I have tried building a custom 3.16 kernel with a few printk:s in > cdc_ncm.c and huawei_cdc_ncm.c, but found nothing suspicious. > > Kernel version (from /proc/version): 3.16 > Environment: Thinkpad L440 64-bit x86 (Intel Core i5-4200M cpu) laptop > with Kubuntu 14.04.1 LTS > Kernel modules: huawei_cdc_ncm,cdc_ncm > > Workaround: Bring up the device with > AT^NDISDUP=1,1,"internet.telenor.se" instead. Also worth noting is > that AT+CGACT=1,1 does not freeze the control connection if using > /dev/ttyUSB0. Regardless of the actual issue in the kernel driver, if any, NDISDUP in the cdc-wdm device is the way to go to connect that modem. -- Aleksander https://aleksander.es -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
