Bug#833918: linux: Please enable cdc_ncm and cdc_mbim in d-i to support 'Dell 4-in-1 Adapter' Ethernet

[Bjørn Mork <bjorn@mork.no>]

John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> writes:

> This adapter uses the cdc_ncm/cdc_mbim kernel modules which are currently being disabled for
> debian-installer as those were suspected to be used by modems only [2], which is not the
> case, however.

cdc_mbim is modem-only. cdc_ncm is not.

The reason you see cdc_mbim loaded is because of an oddity in the MBIM
spec, allowing an USB interface to be both NCM and MBIM depening on the
active altsetting. The cdc_mbim driver is therefore matching NCM
interfaces to be able to detect this sort of dual function.  But that's
completely irrelevant to your ethernet adapter.  MBIM cannot be used on
an ethernet (it has no no L2 headers).

By avoiding cdc_mbim, you can also drop the cdc_wdm dependency.


> [ 9105.605635] cdc_ncm 2-1.1:1.5: MAC-Address: 9c:eb:e8:20:f5:5b
> [ 9105.605640] cdc_ncm 2-1.1:1.5: setting rx_max = 16384
> [ 9105.605743] cdc_ncm 2-1.1:1.5: setting tx_max = 16384
> [ 9105.605991] cdc_ncm 2-1.1:1.5 usb0: register 'cdc_ncm' at usb-0000:00:14.0-1.1, CDC NCM, 9c:eb:e8:20:f5:5b
> [ 9105.680400] cdc_ncm 2-1.1:1.5 enx9cebe820f55b: renamed from usb0

See?  This is only using cdc_ncm and will work fine even if cdc_mbim is unavailable.


Bjørn