[Bug 220166] New: The g_webcam UVC gadget driver fails to enumerate properly on Windows 11, returning USB\DEVICE_DESCRIPTOR_FAILURE in Device Manager, while other USB gadgets (g_serial, g_mass_storage) work correctly on the same hardware and Windows version. This represent

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220166

            Bug ID: 220166
           Summary: The g_webcam UVC gadget driver fails to enumerate
                    properly on Windows 11, returning
                    USB\DEVICE_DESCRIPTOR_FAILURE in Device Manager, while
                    other USB gadgets (g_serial, g_mass_storage) work
                    correctly on the same hardware and Windows version.
                    This represent
           Product: Drivers
           Version: 2.5
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: USB
          Assignee: drivers_usb@kernel-bugs.kernel.org
          Reporter: joshcabarrus@gmail.com
        Regression: No

System Information

Hardware: Raspberry Pi Zero W Rev 1.1 (BCM2835, Revision: 9000c1)
Kernel: Linux 6.12.25+rpt-rpi-v6 #1 Raspbian (armv6l)
USB Controller: dwc2 20980000.usb
Host OS: Windows 11 (up to date)

Problem Description
When g_webcam is loaded and the Pi Zero W is connected to Windows 11 via USB:

g_webcam behavior:

Loads successfully on Pi: g_webcam ready, bound driver g_webcam
UDC state remains: not attached (never reaches configured)
Windows shows: Unknown USB Device (Device Descriptor Request Failed)
Hardware ID: USB\DEVICE_DESCRIPTOR_FAILURE


g_serial behavior (control test):

Loads successfully: g_serial ready, bound driver g_serial
UDC state becomes: configured
Windows properly recognizes as COM port device



Steps to Reproduce
bash# On Raspberry Pi Zero W:
sudo modprobe g_webcam
cat /sys/class/udc/20980000.usb/state  # Shows: not attached

# Connect USB cable to Windows 11
# Result: "Unknown USB Device" in Device Manager

# Control test:
sudo rmmod g_webcam
sudo modprobe g_serial  
cat /sys/class/udc/20980000.usb/state  # Shows: configured
# Result: Working COM port in Windows
Expected vs Actual Behavior
Expected: g_webcam should enumerate successfully on Windows 11 like other
gadgets and previous Windows versions.
Actual: Windows 11 rejects the USB device descriptors with
DEVICE_DESCRIPTOR_FAILURE.
Analysis
The issue appears to be Windows 11's stricter USB descriptor validation. The
g_webcam UVC descriptors may not fully comply with:

USB Video Class specification requirements
Windows 11's enhanced USB security validation
Microsoft's USB descriptor formatting standards

Loaded Modules
g_webcam               16384  0
usb_f_uvc              77824  5  
uvc                    12288  1 usb_f_uvc
libcomposite           69632  17 usb_f_acm,usb_f_uvc,g_webcam
dwc2                  176128  0
Kernel Messages
g_webcam gadget.0: uvc: uvc_function_bind()
g_webcam gadget.0: Webcam Video Gadget  
g_webcam gadget.0: g_webcam ready
dwc2 20980000.usb: bound driver g_webcam
Impact
This affects numerous Raspberry Pi Zero W webcam projects and tutorials that
previously worked with Windows. Users report this issue across multiple Pi Zero
W webcam implementations.
Suggested Investigation Areas

USB Descriptor Compliance: Review g_webcam's USB descriptors against latest USB
Video Class specification
Windows 11 Requirements: Compare descriptor format with Windows 11's validation
requirements
VID/PID Issues: Verify Vendor/Product ID configuration doesn't trigger Windows
driver conflicts
UVC Version Compatibility: Check if UVC version advertised matches capabilities
provided

Request
Could the maintainers investigate updating g_webcam's USB descriptors to meet
Windows 11's stricter validation requirements? The fact that g_serial works but
g_webcam fails suggests this is a descriptor-specific issue rather than
hardware or driver framework problem.
Additional Information Available
I can provide:

USB protocol analyzer captures
Testing with different Windows versions
Comparison with working UVC implementations
Further diagnostic information as needed

Thank you for maintaining the USB gadget subsystem.
Reporter: [Your name and email]
Date: May 27, 2025

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