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by
TRM250 only shows the /dev/ttyUSB0 and /dev/ttyUSB1 device on a Linux system (Ubuntu 18.4 - 20.10, Raspbian 10). /dev/ttyUSB2 and /dev/ttyUSB3 are missing. /sys/kernel/debug/usb/devices shows (none) as driver instead of option. How can this be fixed?
by

This is a Linux Kernel bug. A fix was published 2020-12-01.

Fix: https://github.com/torvalds/linux/commit/c98fff7332dbd6e028969f8c2bda3d7bc7a024d8

The fix changes the number of serial interfaces from 2 to 4 in the 'option' driver.

1 Answer

0 votes
by anonymous

Hi,

1. How are you identifying ttyUSB devices? Do you run any particular command? Try using dmesg | grep tty and then see if you get what you expected to get.

2. Are you using VM or running it on actual linux software? If you're on VM, make sure you select the modem in USB settings as an active device.

EB.

by

Hi,

I'm using a Raspberry PI 2 B (Raspian 10). I've also tested the Modem at a Ubuntu 20.04 computer (with the same result).

The Raspi has no serial USB interfaces when the modem is not plugged in. 

After plugging in the TRM250 modem, I got the linux devices ttyUSB0 and ttyUSB1. 

Here is the dmesg output:

[245635.466749] usb 1-1.2.3: new high-speed USB device number 11 using dwc_otg

[245635.599310] usb 1-1.2.3: New USB device found, idVendor=2c7c, idProduct=0296, bcdDevice= 0.00

[245635.599338] usb 1-1.2.3: New USB device strings: Mfr=3, Product=2, SerialNumber=4

[245635.599380] usb 1-1.2.3: Product: Qualcomm CDMA Technologies MSM

[245635.599398] usb 1-1.2.3: Manufacturer: Qualcomm, Incorporated

[245635.599414] usb 1-1.2.3: SerialNumber: 8eb94a57

[245635.602162] option 1-1.2.3:1.0: GSM modem (1-port) converter detected

[245635.602965] usb 1-1.2.3: GSM modem (1-port) converter now attached to ttyUSB0

[245635.604325] option 1-1.2.3:1.1: GSM modem (1-port) converter detected

[245635.605132] usb 1-1.2.3: GSM modem (1-port) converter now attached to ttyUSB1

[245635.617256] qmi_wwan 1-1.2.3:1.4: cdc-wdm0: USB WDM device

[245635.619451] qmi_wwan 1-1.2.3:1.4 wwan0: register 'qmi_wwan' at usb-3f980000.usb-1.2.3, WWAN/QMI device, 06:cd:9d:0e:35:72

Here is the modem part of the /sys/kernel/debug/usr/devices file:
T:  Bus=01 Lev=03 Prnt=04 Port=02 Cnt=03 Dev#= 11 Spd=480  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=2c7c ProdID=0296 Rev= 0.00
S:  Manufacturer=Qualcomm, Incorporated
S:  Product=Qualcomm CDMA Technologies MSM
S:  SerialNumber=8eb94a57
C:* #Ifs= 5 Cfg#= 1 Atr=e0 MxPwr=500mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=option
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=option
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=83(I) Atr=03(Int.) MxPS=  64 Ivl=2ms
E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=fe Prot=ff Driver=(none)
E:  Ad=85(I) Atr=03(Int.) MxPS=  64 Ivl=2ms
E:  Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan
E:  Ad=87(I) Atr=03(Int.) MxPS=  64 Ivl=2ms
E:  Ad=88(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
by anonymous
Hi,

Could you please swap the cables? It could be that you're using not a data cable and that's why not all interfaces are showing up.

Also, do you have any windows machine that you could test this on? If windows would show the same result it would mean that there's something up with the device or the cable.

EB.
by
I've changed the cabel and also tried another TRM250:

Windows shows one more serial interface (AT command):

Quectel USB AT Port

Quectel USB DM Port

Quectel USB NMEA Port
by anonymous
Does it show that one serial interface with another TRM or the old one?