I have 3 different MC7455 modules that I have been testing. One of them is Rev A. Another one is Rev B. The last one is Rev C. I am testing these on an OpenWRT router that is based on the Ralink MT7620 processor and MIPS 24kc architecture. I am currently using OpenWRT/LEDE 18.06 with kernel 4.14.70. I have compiled the firmware with both the qmi_wwan/qcserial and GobiNet/GobiSerial driver. To toggle between the drivers, I use a script which removes the module from the kernel (i.e. insmod and/or rmmod).
All 3 modules have been configured to be in QMI mode with one RMNET enabled (AT!USBCOMP=1,1,10D) and SIM based firmware switching (AT!IMPREF=“AUTO-SIM”). When using the qmi_wwan/qcserial drivers, all 3 modules are detected correctly, and I am able to issue AT commands to all of them in a terminal. However, all utilities that use libqmi (i.e. qmicli, qmi-network) along with uqmi do NOT work with the Rev A module. The QMI commands issued by the applications all time out on it. The other 2 modules (Rev B and C) work just fine with the utilities and I am able to connect to the carrier networks that I have tested with them (AT&T, Verizon, T-Mobile).
When I use the GobiNet/GobiSerial drivers, all 3 modules are detected correctly, and I am able to issue AT commands to all of them in a terminal. I have tested the modules with these drivers on a desktop PC running Ubuntu 18.04 and was able to use the Connection Manager application (provided in the SDK) to successfully connect to 3 different carrier networks above. However, due to the lack of availability of the needed precompiled libraries and SDK process needed (for the MIPS 24kc architecture) in the SDK package, I am unable to compile the applications for the router’s architecture. Therefore, I am currently unable to test the applications on the router. I have been in contact with source to find out whether they can provide me with the needed precompiled libraries and slqssdk, but that is a separate issue. I believe I may have to make this sort of request through a distributor.
So here is my first question. Is there any configuration change or AT command(s) that I can use to enable the Rev A module to work with libqmi based utilities and/or uqmi with the qmi_wwan driver? I’d rather not use MBIM mode since I’d like to be able to access everything that I can in QMI mode. Also, since I currently do not have a complete solution to manage connectivity via the Gobi SDK in the router’s environment, these are my only options.
Now on to my second issue. I recently upgraded another MC7455 module to the latest carrier firmware for Generic, AT&T, Sprint, and Verizon (version 2.30.01.01). I have another SIM card from FreedomPop that I use for testing. They are an MVNO that utilizes AT&T’s network to my knowledge. In the previous firmwares (2.24.05.06), when I used this SIM, the auto SIM switching feature would load the Generic firmware, and I would use a custom APN for FreedomPop (fp.com.attz). This worked perfectly. In the new firmware, the auto SIM switching feature is loading the AT&T firmware instead. This has caused some glitches from time to time. Another thing that I noticed is that if I use a Verizon SIM, then use a T-Mobile SIM, the new firmware’s auto SIM switching is NOT changing to Generic like the previous firmware used to.
So here is my second question. Am I able to download the previous carrier firmware and downgrade? If so, where can I download the files? I cannot find them on source.
Any help would be really appreciated.