# EM7355 Kernel configs **URL:** \ **Category:** IoT Modules\ **Created:** [November 12, 2019, 9:08pm UTC](https://forum.sierrawireless.com/t/em7355-kernel-configs/18298 "2019-11-12T21:08:56Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![hjamal](https://avatars.discourse-cdn.com/v4/letter/h/a88e4f/32.png) [@hjamal](https://forum.sierrawireless.com/u/hjamal)\ **Post date:** [November 12, 2019, 9:08pm UTC](https://forum.sierrawireless.com/t/em7355-kernel-configs/18298/1 "2019-11-12T21:08:56Z")
Hello, We’re trying to use EM7355 in Jetson Nano. The kernel is 4.9.140. I’ve not been able to get the device working by enabling the following configs CONFIG\_USB\_SIERRA\_NET=y CONFIG\_USB\_SERIAL\_SIERRAWIRELESS=y CONFIG\_USB\_SERIAL\_QUALCOMM=y CONFIG\_USB\_NET\_QMI\_WWAN=y CONFIG\_USB\_SERIAL\_WWAN=y CONFIG\_MII=y I find the device ID is supported in CONFIG\_USB\_SERIAL\_QUALCOMM, qcserial.c; but it fails to load the driver at “if (intf-\>desc.bInterfaceClass != USB\_CLASS\_VENDOR\_SPEC)”; the interface class it gets [USB\_CLASS\_COMM] and [USB\_CLASS\_CDC\_DATA]. Then I add the device ID to another driver file CONFIG\_USB\_SERIAL\_SIERRAWIRELESS, sierra.c and I can see that it installed two serial ports ttyUSB0 and ttyUSB1. I see in the dmesg log “sierra ttyUSB0: sierra\_submit\_rx\_urbs: submit urb failed”. I also tried to talk to the modem at 9600bps using minicom and got no answer by typing ‘at’, it may be in data mode. I think this is not the correct driver. Some information lsusb -t /: Bus 02.Port 1: Dev 1, Class=root\_hub, Driver=tegra-xusb/4p, 5000M /: Bus 01.Port 1: Dev 1, Class=root\_hub, Driver=tegra-xusb/5p, 480M |\_\_ Port 1: Dev 2, If 12, Class=Communications, Driver=sierra, 480M |\_\_ Port 1: Dev 2, If 13, Class=CDC Data, Driver=sierra, 480M cat /sys/kernel/debug/usb/devices T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=00(\>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 2 P: Vendor=03f0 ProdID=4e1d Rev= 0.06 S: Manufacturer=Sierra Wireless, Incorporated S: Product=HP lt4111 LTE/EV-DO/HSPA+ Gobi 4G Module C: #Ifs= 4 Cfg#= 1 Atr=e0 MxPwr=500mA I: If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver= E: Ad=82(I) Atr=03(Int.) MxPS= 12 Ivl=32ms E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver= E: Ad=84(I) Atr=03(Int.) MxPS= 12 Ivl=32ms E: Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=86(I) Atr=03(Int.) MxPS= 10 Ivl=32ms E: Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver= E: Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms C:\* #Ifs= 2 Cfg#= 2 Atr=e0 MxPwr=500mA A: FirstIf#=12 IfCount= 2 Cls=02(comm.) Sub=0e Prot=00 I:\* If#=12 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=0e Prot=00 Driver=sierra E: Ad=82(I) Atr=03(Int.) MxPS= 64 Ivl=32ms I: If#=13 Alt= 0 #EPs= 0 Cls=0a(data ) Sub=00 Prot=02 Driver=sierra I:\* If#=13 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=sierra E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I need some direction to move forward. Any help is appreciated. Thanks, Hakim ---
**Author:** ![dl5162](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/dl5162/32/2169_2.png) [@dl5162](https://forum.sierrawireless.com/u/dl5162)\ **Post date:** [November 12, 2019, 9:49pm UTC](https://forum.sierrawireless.com/t/em7355-kernel-configs/18298/2 "2019-11-12T21:49:18Z")
Your modem is configured for MBIM without any serial functions. You need the cdc\_mbim driver for that. Or, since you have a dual config, you can switch to the qmi config by writing 1 to the /sys/bus/usb/devices/…/bConfiguration attribute. Then the qcserial and qmi\_wwan drivers should bind ---
**Author:** ![hjamal](https://avatars.discourse-cdn.com/v4/letter/h/a88e4f/32.png) [@hjamal](https://forum.sierrawireless.com/u/hjamal)\ **Post date:** [November 13, 2019, 5:24pm UTC](https://forum.sierrawireless.com/t/em7355-kernel-configs/18298/3 "2019-11-13T17:24:17Z")
Thanks a lot, MBIM, cdc\_mbim driver worked.