Re: PCIe MBIM modem not creating a wwan netdev

[Chris Webb <chris@arachsys.com>]

Chris Webb <chris@arachsys.com> writes:

> Is this a bug (with my modem?) or there something more than the above
> I need to enable for the network device to be created as well as the
> character devices, as in the USB case?

This turns out to be a missing PCI ID for the variant of the RM520M-GL
modem I have. Doing the following got the channels labelled correctly
so the mhi_wwan_mbim driver bound to IP_HW0_MBIM:

diff --git a/drivers/bus/mhi/host/pci_generic.c b/drivers/bus/mhi/host/pci_generic.c
index 08844ee7..7043d366 100644
--- a/drivers/bus/mhi/host/pci_generic.c
+++ b/drivers/bus/mhi/host/pci_generic.c
@@ -620,6 +620,9 @@ static const struct pci_device_id mhi_pci_id_table[] = {
 		.driver_data = (kernel_ulong_t) &mhi_telit_fn980_hw_v1_info },
 	{ PCI_DEVICE(PCI_VENDOR_ID_QCOM, 0x0306),
 		.driver_data = (kernel_ulong_t) &mhi_qcom_sdx55_info },
+	/* RM520N-GL variant with Qualcomm vendor and subvendor ID */
+	{ PCI_DEVICE_SUB(PCI_VENDOR_ID_QCOM, 0x0308, PCI_VENDOR_ID_QCOM, 0x5201),
+		.driver_data = (kernel_ulong_t) &mhi_quectel_rm5xx_info },
 	/* Telit FN990 */
 	{ PCI_DEVICE_SUB(PCI_VENDOR_ID_QCOM, 0x0308, 0x1c5d, 0x2010),
 		.driver_data = (kernel_ulong_t) &mhi_telit_fn990_info },


I wonder if there's an exhaustive list somewhere of the PCI ids used on
these Quectel cards, that might enable me to submit a sensible patch
rather than just an ad hoc fix-up for one combination I've found in
the wild...

I do note quite a bit of 

[  388.122202] sequence number glitch prev=94 curr=0
[  402.513709] sequence number glitch prev=12 curr=0
[  408.708148] sequence number glitch prev=3 curr=0
[  416.915221] sequence number glitch prev=11 curr=0
[  423.032992] sequence number glitch prev=5 curr=0
[  442.724830] sequence number glitch prev=4 curr=0
[  455.594228] sequence number glitch prev=9 curr=0
[  463.810701] sequence number glitch prev=3 curr=0
[  468.970895] sequence number glitch prev=6 curr=0

but assume this is likely to be some kind of modem bug? Interestingly,
the equivalent warning in drivers/net/usb/cdc_ncm.c never fires when
the modem is in USB mode.

Best wishes,

Chris.