I have an RM520N-GL on an OpenWRT box.
I have enabled the MHI kmods and I can see that the modem is recognized and I get a /dev/wwan0at0 port along with the /dev/wwan0mbim0 and /dev/wwan0qdcm0 ports. If I configure the modem with the MBIM protocol, I can get it online.
I would like to use it in QMI mode for efficiency but I’m not getting the /dev/wwan0qmi0 port. Can anyone assist in understanding what do I need to do to get it working?
Thank you.
You usually have to configure the module to either do MBIM or QMI using AT commands.
Setting the USB network mode to QMI:
AT+QCFG="usbnet",0)
It's already in QMI, if I change the data port to USB, it works with QMI.
When I put it in PCIe, seems just to go only MBIM.
I see. I'm not familiar with that specific module, but it seems Waveshare has a bit about it.
A bit down the page they show some AT commands regarding PCIe mode. I don't know if it'll help you.
The channel config for PCIe is statically defined in the driver IIUC.
mhi_quectel_em1xx_channels is referenced by modem_quectel_em1xx_config, which again is referenced by both mhi_quectel_em1xx_info and mhi_quectel_rm5xx_info. The RM520N-GL entry in the pci_device_id table points to mhi_quectel_rm5xx_info.
So you end up with this channel map:
Why do you think QMI is better? I assume this modem supports the QMI MBIM service, so that all the requests are available? Are there any measurements comparing QMI and MBIM framing on the PCIe bus?
Oh, that explains it all, thank you!
Since I patched the vendor/subvendor of my specific SKU of modem in the code, I might as well try to patch the channels but - to answer your question, no, I don't have -any comparison between the two.
I was trying to replicate the setup I had with USB - that used QMI - in PCIe. The curious thing is that the usbnet setting of the modem is set to QMI/RMNET, not MBIM. That's why I get confused on why it works with MBIM.
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