Re: [libusb] Correct use of libusb with composite device

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

In this case, you may want to use libusb xusb example and then post
the full debug output
of `xusb -d 1cbf:0007". Make sure you use the latest 1.0.26 release or
git master.

Best regards,
Xiaofan

On Thu, Jul 13, 2023 at 10:03 AM RisingEdgeIndustries
<su...@ri...> wrote:
>
> So I'm taking the same approach I take when I had these interfaces running as stand alone devices.  My process is below.
>
>
> Call get_device_list()
> Loop through device list to find VID/PID
> Once found open_device() with my VID/PID
> [at this point I get string descriptors and max_packet_size() which works fin]
> I then execute claim_interface() for my device
>
> I can claim interface 0, but when I try interface 1 I get the following error:
> ERROR: failed to claim interface, ret val = -12
> ERROR: code - b'Operation not supported or unimplemented on this platform'
>
> I know from the descriptors during enumeration my second interface is my bulk interface with bInterfaceNumber "1".
>
> I see both interfaces with correct VID/PID in device manager with correct drivers and no icons indicating a problem.  Is there something obvious I'm missing in this process?  This process works fine for non-composite HID only or bulk only.
>
>
> Descriptor data:
>
>
> ----- Device Descriptor -----
> 12 bLength
> 01 bDesc Type
> 00 02 bcdUSB (LSB, MSB)
> 00 bDeviceClass
> 00 bDeviceSubClass
> 00 bDeviceProtocol
> 40 bMaxPacketSize0 - Maximum packet size for Endpoint zero (only 8, 16, 32, or 64 are valid).
> BF 1C idVendor (LSB, MSB)
> 07 00 idProduct (LSB, MSB)
> 00 01 bcdDevice (BCD) (LSB, MSB)
> 01 iManufacturer (string index)
> 02 iProduct (string index)
> 03 iSerialNumber (string index)
> 01 bNumConfigurations (string index)
>
> ----- Configuration Descriptor -----
> 09 bLength
> 02 bDesc Type
> 40 00 wTotalLen  (LSB, MSB)
> 02 bNumInterfaces
> 01 bConfigurationValue
> 00 iConfiguration
> 80 bmAttributes
> 7D bmAttributes
>
> ----- Interface Descriptor -----
> 09 bLength
> 04 bDesc Type
> 00 bInterfaceNumber
> 00 bAlternateSetting
> 02 bNumEndpoints
> 03 bInterfaceClass
> 00 bInterfaceClass
> 00 bInterfaceProtocol
> 00 iInterface
>
> ----- HID Class Descriptor -----
> 09 bLength
> 21 bDesc Type
> 00 02 bcdHID (Hid Spec Release Number) (LSB, MSB)
> 00 bCountryCode (Country code (0x00 for not supported))
> 01 bNumDescriptors (Number of class descriptors)
> 22 bDescriptorType (Report descriptor type)
> 20 00 bDescriptorLength (Report descriptor type) (LSB, MSB)
>
> ----- Endpoint Descriptor -----
> 07 bLength
> 05 bDesc Type
> 81 bEndpointAddress
> 03 bmAttributes
> 40 00 wMaxPacketSize (LSB, MSB)
> 01 bInterval
>
> ----- Endpoint Descriptor -----
> 07 bLength
> 05 bDesc Type
> 01 bEndpointAddress
> 03 bmAttributes
> 40 00 wMaxPacketSize (LSB, MSB)
> 01 bInterval
>
> ----- Interface Descriptor -----
> 09 bLength
> 04 bDesc Type
> 01 bInterfaceNumber
> 00 bAlternateSetting
> 02 bNumEndpoints
> FF bInterfaceClass
> 00 bInterfaceClass
> 00 bInterfaceProtocol
> 00 iInterface
>
> ----- Endpoint Descriptor -----
> 07 bLength
> 05 bDesc Type
> 82 bEndpointAddress
> 02 bmAttributes
> 40 00 wMaxPacketSize (LSB, MSB)
> 00 bInterval
>
> ----- Endpoint Descriptor -----
> 07 bLength
> 05 bDesc Type
> 02 bEndpointAddress
> 02 bmAttributes
> 40 00 wMaxPacketSize (LSB, MSB)
> 00 bInterval
>
>
>
>
> On Wed, Jul 12, 2023 at 8:35 PM Xiaofan Chen <xia...@gm...> wrote:
>>
>> There is no limitation for your use case. Open the device normally and claim the
>> correct interface (interface 1 in your case).
>>
>>  libusb_detach_kernel_driver() is not supported under Windows so it is
>> not relevant.
>>
>> The limitations are mainly with things like IAD and CDC-ACM, not your use case.
>> 1) https://github.com/libusb/libusb/pull/965 (PR merged, it will be in
>> future 1.0.27 release)
>> 2) https://github.com/libusb/libusb/issues/1238
>>
>> Best regards,
>> Xiaofan
>>