Quectel RM520N-GL via PCIe with ModemManager

[Hagler Johann]

Hi,
i’m trying to use a Quectel RM520N-GL modem via PCIe on an Embedded Linux System (Kernel 6.1.70) in connection with ModemManager (1.22.0).
I tried with the following kernel config:

CONFIG_MHI_BUS=y
CONFIG_MHI_BUS_PCI_GENERIC=y
CONFIG_MHI_NET=y

which seems to create a correct data channel (interface mhi_hwip0).
Also those devices are created:
dl-router-00002[TEST-CR-1]:~# ls /sys/bus/mhi/devices/
mhi0  mhi0_DIAG  mhi0_IPCR  mhi0_IP_HW0  mhi0_MBIM  mhi0_QMI

However it wouldn’t create a suitable control channel:
Aug 04 19:10:55 dl-router-00002 ModemManager[1231]: [1754327455.502771] [plugin-manager] task 3: still 1 running probes (0 active): mhi_hwip0
Aug 04 19:10:55 dl-router-00002 ModemManager[1231]: [1754327455.502828] [plugin-manager] task 3: no active tasks to probe
Aug 04 19:10:55 dl-router-00002 ModemManager[1231]: [1754327455.502879] [plugin-manager] task 3,mhi_hwip0: deferred task completed, no suggested plugin
Aug 04 19:10:55 dl-router-00002 ModemManager[1231]: [1754327455.502935] [plugin-manager] task 3,mhi_hwip0: finished in '4.009758' seconds
Aug 04 19:10:55 dl-router-00002 ModemManager[1231]: [1754327455.503017] [plugin-manager] task 3,mhi_hwip0: not supported by any plugin
Aug 04 19:10:55 dl-router-00002 ModemManager[1231]: [1754327455.503091] [device /sys/devices/platform/bus at 5f000000/5f010000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/0000:02:05.0/0000:cb:00.0] fully ignoring port mhi_hwip0 from now on

I then tried adding
CONFIG_QRTR=y
CONFIG_QRTR_MHI=y

Now it seems that the ModemManager can talk to the modem via QMI :
Aug 01 20:24:06 dl-router-00002 ModemManager[10468]: [1754072646.499104] [base-manager] port qrtr3 is first in device qcom-soc
Aug 01 20:24:06 dl-router-00002 ModemManager[10468]: [1754072646.499654] [plugin-manager] task 0: new support task for device: qcom-soc
Aug 01 20:24:06 dl-router-00002 ModemManager[10468]: [1754072646.499899] [qrtr3/probe] port type hint detected in udev tag: ID_MM_PORT_TYPE_QMI
Aug 01 20:24:06 dl-router-00002 ModemManager[10468]: [1754072646.499986] [qrtr3/probe] port type hints loaded: AT no, QMI yes, MBIM no, QCDM no, AUDIO no, GPS no

But the ModemManager fails to recognize the mhi_hwip0 interface as the related data channel.

Does anyone know how get this to work?

Many Thanks,
Joe


---

Johann Hagler

Software Engineer



Mission Embedded GmbH

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1100 Vienna, Austria



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