[libusb] libusb_bulk_transfer() return timeout error and transferred set to 0

[benjamin_t <tan...@gm...>]

Hi,
    I'm attempting to write to a bulk endpoint with libusb_bulk_transfer,
and got a strange problem. It returns with a TIMEOUT_ERROR, and the
transferred parameter was set to 0, which indicates no data was sent.

The interface descriptor info is as below:
Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           4
      bInterfaceClass       220 Diagnostic
      bInterfaceSubClass    160 
      bInterfaceProtocol    176 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0019  1x 25 bytes
        bInterval              10
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0019  1x 25 bytes
        bInterval              10
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              10
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              10

And here is my test code
    int   rv = 0;
    rv = libusb_init(NULL);
    if (rv < 0) {
	std::cout << "*** initial USB lib failed!" << std::endl;
	return -1;
    }
    libusb_set_debug(NULL, 4);
    struct libusb_device_handle *usb_handle;
	usb_handle = libusb_open_device_with_vid_pid(NULL, USB_VENDOR_ID,
USB_PRODUCT_ID);
    int ret = libusb_claim_interface(usb_handle, 0);

    unsigned char read_buf[64];
    unsigned char send_buf[25] = {0};
    int transferred;
    ret = libusb_bulk_transfer(usb_handle, 0x2, send_buf, 64,  &transferred,
1000);
    std::cout << "tran " << transferred << std::endl;      // output 0
    std::cout << ret << std::endl;                                 // output
-7
    libusb_bulk_transfer(usb_handle, 0x82, read_buf, 64, &transferred,
1000);
    PrintBuf(read_buf, 64);

The code above works fine when 0x2 and 0x82 was set to 0x1 and 0x81. It
seems like the 0x2 endpoint was not working. Any idea what would cause that?
Thanks in advance!






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