MC7455 not recognized at boot

Hello
I’m working on a IoT project using MC7455 modem as communication module.
The host board is the IMX7 DUAL COM BOARD di Embedded Artists
https://www.embeddedartists.com/products/com/imx7dual_com.php

I performed the following test steps:

  1. Board powered off – Modem installed on PCIe interface.
  2. Board power on – kernel starts but modem is not recognized.
  3. After login lsusb command is sent, modem not recognized.
  4. Modem removed from the PCIe interface and inserted again

Result:
usb 1-1.1: new high-speed USB device number 3 using ci_hdrc
usb 1-1.1: config 1 has an invalid interface number: 8 but max is 4
usb 1-1.1: config 1 has an invalid interface number: 10 but max is 4
usb 1-1.1: config 1 has no interface number 1
usb 1-1.1: config 1 has no interface number 4

sending again lsusb:

Bus 001 Device 003: ID 1199:9071
Bus 001 Device 002: ID 0424:2514
Bus 001 Device 001: ID 1d6b:0002

Sending usb-devices:

T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 1
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=1d6b ProdID=0002 Rev=04.01
S: Manufacturer=Linux 4.1.15-2.0.3+geb0b90b ehci_hcd
S: Product=EHCI Host Controller
S: SerialNumber=ci_hdrc.1
C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub

T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=480 MxCh= 3
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=02 MxPS=64 #Cfgs= 1
P: Vendor=0424 ProdID=2514 Rev=0b.b3
C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=2mA
I: If#= 0 Alt= 1 #EPs= 1 Cls=09(hub ) Sub=00 Prot=02 Driver=hub

T: Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=480 MxCh= 0
D: Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
P: Vendor=1199 ProdID=9071 Rev=00.06
S: Manufacturer=Sierra Wireless, Incorporated
S: Product=Sierra Wireless MC7455B Qualcomm® Snapdragon™ X7 LTE-A
S: SerialNumber=LQ73958578031020
C: #Ifs= 5 Cfg#= 1 Atr=a0 MxPwr=500mA
I: If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
I: If#=10 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
I: If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
I: If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)

So my questions are:
Why the modem is not recognized automatically at power on?
According to the logs above, Is the modem recognized correctly after the hotplug?

Searching on Sierra Wireless forum I found this thread
https://forum.sierrawireless.com/t/mc7455-usb-device-disconnects-immediately/9415/1

Could it be a problem related to USB3 pins?

Thanks in advance

Massimiliano

Hi,

At least in my case MC7455 was not recognized by Qotom minipc board at all. I turned out to be the USB3 pin mapping as described here: https://techship.com/faq/38/. Your usb-devices looks same as what I have.

Jyrki