MHI on 5G modems

[Koen Vandeputte]

Hi All,

I'm currently working on adding MHI support within OpenWRT. (kernel 5.15.59)

I have a few modems laying around here:

- Sierra Wireless EM9191
- Telit FN980
- Fibocom FM150-AE

On all 3 of them, MHI seems to enumerate correctly:

[    8.258921] mhi-pci-generic 0000:01:00.0: BAR 0: assigned [mem 
0x01100000-0x01100fff 64bit]
[    8.267488] mhi-pci-generic 0000:01:00.0: enabling device (0140 -> 0142)
[    8.276817] mhi mhi0: Requested to power ON
[    8.288905] mhi mhi0: Power on setup success
[    8.341370] mhi mhi0: Wait for device to enter SBL or Mission mode

Exposed devices:

/dev/wwan0mbim0
/dev/wwan0qcdm0
/dev/wwan0qmi0

And a network device:

mhi_hwip0


Following kernel SYMS are enabled:

CONFIG_MHI_BUS=m
CONFIG_MHI_BUS_DEBUG=y
CONFIG_MHI_BUS_PCI_GENERIC=m
CONFIG_MHI_NET=m
CONFIG_MHI_WWAN_CTRL=m
CONFIG_MHI_WWAN_MBIM=m
CONFIG_WWAN=m


Now the problem is, when sending QMI traffic towards wwan0qmi0, I never 
get a reply back on any of them.
When using cdc-wdm  or when wwan0qmi0 is exposed over usb, it works,
but as soon as wwan0qmi0 is exposed over pcie, it fails.

Does anyone have any clue what is missing here?



Thanks!

Koen