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net: usb: cdc_ncm: add Apple Silicon MacBook Air (05ac:1903) device ID

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The Apple Silicon MacBook Air exposes a CDC-NCM interface (05ac:1903)
when connected host-to-host over USB-C.

The device tested is an Apple MacBook Air (13-inch, M1, 2020), Model A2337
(MacBookAir10,1) with an Apple M1 chip. Unlike
commit a5148bc2fa ("net: usb: cdc_ncm: add Apple Mac USB-C direct networking quirk")
which hypothesized all Apple Silicon Macs share PID 0x1905 ("Mac"), this
M1 MacBook Air exposes PID 0x1903 with iProduct string "MacBook Air".

Like other Apple CDC-NCM peripherals (0x1902 and 0x1905), Apple's
firmware omits the CDC status interrupt endpoint. This causes the
standard cdc_ncm probe to fail with a missing endpoint error:

  cdc_ncm 1-7:1.0: bind() failure
  cdc_ncm: probe of 1-7:1.0 failed with error -22

Add device ID 05ac:1903 to cdc_devs binding to
apple_private_interface_info so the driver bypasses the interrupt
check and initializes host-to-host networking successfully:

  cdc_ncm 1-7:1.0 usb0: register 'cdc_ncm' at usb-...,
  CDC NCM (Apple Private), ...

Relevant 'lsusb -v' descriptor output:

  Device Descriptor:
    bcdUSB               2.10
    idVendor           0x05ac Apple, Inc.
    idProduct          0x1903 MacBook Air
    bcdDevice           10.01
    iManufacturer           1 Apple Inc.
    iProduct                2 MacBook Air
    Configuration Descriptor:
      Interface Descriptor:
        bInterfaceNumber        0
        bInterfaceClass         2 Communications
        bInterfaceSubClass     13 CDC NCM
        bNumEndpoints           0
      Interface Descriptor:
        bInterfaceNumber        1
        bInterfaceClass        10 CDC Data
        bNumEndpoints           2
      Interface Descriptor:
        bInterfaceNumber        2
        bInterfaceClass         2 Communications
        bInterfaceSubClass     13 CDC NCM
        bNumEndpoints           0
      Interface Descriptor:
        bInterfaceNumber        3
        bInterfaceClass        10 CDC Data
        bNumEndpoints           2

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Signed-off-by: Divyanshu Jha <divyanshuj2006@gmail.com>
Link: https://patch.msgid.link/20261024122051.14427-1-divyanshuj2006@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Divyanshu Jha 2026-10-24 17:50:51 +05:30 committed by Jakub Kicinski
parent 0de4e69cd0
commit a8d0451967
1 changed files with 6 additions and 0 deletions
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6
drivers/net/usb/cdc_ncm.c
View File

@ -2022,6 +2022,12 @@ static const struct usb_device_id cdc_devs[] = {
{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x1902, 2),
.driver_info = (unsigned long)&apple_private_interface_info,
},
{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x1903, 0),
.driver_info = (unsigned long)&apple_private_interface_info,
},
{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x1903, 2),
.driver_info = (unsigned long)&apple_private_interface_info,
},
{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x1905, 0),
.driver_info = (unsigned long)&apple_private_interface_info,
},