From a8d0451967fc0a34c4b0c21368986a81b4e14862 Mon Sep 17 00:00:00 2001 From: Divyanshu Jha Date: Sat, 24 Oct 2026 17:50:51 +0530 Subject: [PATCH] net: usb: cdc_ncm: add Apple Silicon MacBook Air (05ac:1903) device ID 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 a5148bc2fa27 ("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 Signed-off-by: Divyanshu Jha Link: https://patch.msgid.link/20261024122051.14427-1-divyanshuj2006@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/usb/cdc_ncm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index 3bd7cb66f3fc..19db5a668dcb 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -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, },