libusb-devel

[libusb] DOMException: Failed to execute 'controlTransferIn' on 'USBDevice': A transfer error has occurred.

[<jo...@be...>]

Hi,

 

I'm trying to use libusb in a Qt WebAssembly app via the Emscripten port.
It's a port of driver that works under Linux & Windows. The first call to
libusb_get_device_list() is failing with the console message:

 

    DOMException: Failed to execute 'controlTransferIn' on 'USBDevice': A
transfer error has occurred.

 

On Windows 11 using Chrome, Edge and Opera.

 

Tracing through the code, in emscripten_webusb.cpp
makeControlTransferPromise() calls controlTransferIn with "request_type":
"standard", "recipient": "device", "request": 6, "wValue": 0x100, "wIndex":
0, "wLength": 0x12 before this error. 

 

Any idea why this might be failing? If I perform the same controlTransfer in
JavaScript, it works OK.

 

Thanks,

Jon

 

 

Re: [libusb] DOMException: Failed to execute 'controlTransferIn' on 'USBDevice': A transfer error has occurred.

[Xiaofan C. <xia...@gm...>]

On Sat, May 4, 2024 at 5:06 PM <jo...@be...> wrote:
>
> I’m trying to use libusb in a Qt WebAssembly app via the Emscripten port.
> It’s a port of driver that works under Linux & Windows. The first call to
>  libusb_get_device_list() is failing with the console message:
>
>     DOMException: Failed to execute 'controlTransferIn' on 'USBDevice':
> A transfer error has occurred.
>
> On Windows 11 using Chrome, Edge and Opera.
>
> Tracing through the code, in emscripten_webusb.cpp makeControlTransferPromise()
> calls controlTransferIn with "request_type”: “standard", "recipient”: “device", "request”: 6,
> "wValue”: 0x100, "wIndex”: 0, "wLength”: 0x12 before this error.
>
> Any idea why this might be failing? If I perform the same controlTransfer in
> JavaScript, it works OK.

As per libusb Wiki, the status of WebAssembly + WebUSB support is EXPERIMENTAL.
https://github.com/libusb/libusb/wiki

The above Wiki has a link to the following blog post which talks about the
difficulties in enumerating the devices using web applications.
https://web.dev/articles/porting-libusb-to-webusb#using-the-port

If that does not help, please create a new issue in libusb github.
https://github.com/libusb/libusb/issues

-- 
Xiaofan

Re: [libusb] DOMException: Failed to execute 'controlTransferIn' on 'USBDevice': A transfer error has occurred.

[<jo...@be...>]

Hi,

>The above Wiki has a link to the following blog post which talks about the difficulties
> in enumerating the devices using web applications.
>https://web.dev/articles/porting-libusb-to-webusb#using-the-port

Thanks. After some more debug, I think the problem relates to the value of MAX_CTRL_BUFFER_LENGTH in emscripten_webusb.cpp. It's currently 4096. There's a comment that says transfers may fail if this is too big - and reducing it to 255 seems to enable the code to work on Windows.

>If that does not help, please create a new issue in libusb github.
>https://github.com/libusb/libusb/issues

Have added: https://github.com/libusb/libusb/issues/1493 with some more details.

Cheers,
Jon