usb_get_device_descriptor()

usb_new_device() -> usb_get_device_descriptor()

usb_get_device_descriptor() 读入整个设备描述结构

设备中有：设备描述块 USB_DT_DEVICE

接口描述块 USB_DT_INTERFACE

配置描述块 USB_DT_CONFIG

端口描述块 USB_DT_ENDPOINT

从设备读入的16位整数都是"little ending"的格式，所以要把它们转换成主机CPU所采用的格式

int usb_get_device_descriptor(struct usb_device *dev)

{

int ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, &dev->descriptor,

sizeof(dev->descriptor));

if (ret >= 0) {

le16_to_cpus(&dev->descriptor.bcdUSB);

le16_to_cpus(&dev->descriptor.idVendor);

le16_to_cpus(&dev->descriptor.idProduct);

le16_to_cpus(&dev->descriptor.bcdDevice);

}

return ret;

}