Re: [PATCH net-next] net: usb: cdc_ncm: add Apple Mac USB-C direct networking quirk

[Simon Horman]

On Wed, Apr 29, 2026 at 06:57:39PM +0100, Alex Cheema wrote:
> Apple Silicon Macs expose two CDC NCM "private" data interfaces over
> USB-C with VID:PID 0x05ac:0x1905 and product string "Mac". This is the
> same protocol Apple already ships on iPhone (0x05ac:0x12a8) and iPad
> (0x05ac:0x12ab) for RemoteXPC since iOS 17 -- both data interfaces lack
> an interrupt status endpoint, so they rely on the FLAG_LINK_INTR-
> conditional bind path introduced in commit 3ec8d7572a69 ("CDC-NCM: add
> support for Apple's private interface").
> 
> The id_table currently has entries for iPhone and iPad but not for the
> Mac. Without a match, cdc_ncm falls through to the generic CDC NCM
> class-match entry, which uses the FLAG_LINK_INTR-having cdc_ncm_info
> struct, so bind_common() fails on the missing status endpoint and no
> netdev appears.
> 
> Add id_table entries for both interface numbers (0 and 2) of the Mac,
> bound to the existing apple_private_interface_info driver_info.
> 
> Verified empirically on a Mac Studio M3 Ultra running macOS 26.5: when
> a Mac is connected via USB-C, ioreg shows VID 0x05ac, PID 0x1905,
> product string "Mac", with two NCM data interfaces at numbers 0 and 2.
> The same PID is presented by all current Apple Silicon Mac models
> (MacBook Pro/Air, Mac mini, Mac Studio across the M-series), mirroring
> Apple's single-PID-per-family pattern from iPhone/iPad.
> 
> After this patch, plugging a Mac into a Linux host running the patched
> kernel produces two enx... interfaces (one per data interface),
> "ip -br link" lists them as UP, and standard userspace networking
> (DHCP, NetworkManager shared mode, etc.) works without any modprobe
> overrides or out-of-tree modules.
> 
> Signed-off-by: Alex Cheema <alex@xxxxxxxxxxx>

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>