Onboard Sim slot selection

[charlesrg]

How does the M.2 PCI-E/USB modem finds the Sim cards ?

I've a Compex WPJ428 with dual SIM slots and wondering how the SIM slot selection is made.
So far I'm running modemmanger and I can see the modem and it does not find the sim on slot0.

Code: Select all

root@OpenWrt:/# mmcli -m 0
  -----------------------------------
  General  |               dbus path: /org/freedesktop/ModemManager1/Modem/0
           |               device id: 7b442dea623c3bf39ac9792800ac53c5ee552c49
  -----------------------------------
  Hardware |            manufacturer: Dell Inc.
           |                   model: DW5821e Snapdragon X20 LTE
           |       firmware revision: T77W968.F1.0.0.3.5.GC.009
           |                          020
           |          carrier config: GCF
           | carrier config revision: 08E00009
           |            h/w revision: DW5821e Snapdragon X20 LTE
           |               supported: gsm-umts
           |                 current: gsm-umts
           |            equipment id: 355446090607XXX
  -----------------------------------
  System   |                  device: /sys/devices/platform/soc/60f8800.usb2/6000000.dwc3/xhci-hcd.1.auto/usb3/3-1
           |                 drivers: cdc_mbim, option
           |                  plugin: dell
           |            primary port: cdc-wdm0
           |                   ports: cdc-wdm0 (mbim), ttyUSB0 (at), ttyUSB2 (gps), wwan0 (net),
           |                          ttyUSB1 (at), ttyUSB3 (qcdm)
  -----------------------------------
  Status   |                   state: failed
           |           failed reason: sim-missing
           |             power state: low
           |          signal quality: 0% (cached)
  -----------------------------------
  Modes    |               supported: allowed: any; preferred: none
           |                 current: allowed: any; preferred: none
  -----------------------------------
  IP       |               supported: ipv4, ipv6, ipv4v6
root@OpenWrt:/# lsusb
Bus 003 Device 002: ID 413c:81d7 Dell Computer Corp.
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 0781:55a0 SanDisk Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

I'm wondering what kind of device is a SIM card slot so I could query it and see if I can read the sim info.
Anyone knows ?

[charlesrg]

Found some info using the GPIO pins to set:
gpioset 1000000.pinctrl 3=0

However I don't have a way to test reading the sim card. I find it strange that the Modem has a direct path to talk to the sim, it must be exposed in some other way.