[UVC] Get hub hardware port with device before UVC_OPEN (IEC-94)

[lijunru-hub]

On the IDF branch hotfix/usb_hub_uninstall, a new field for the hardware port of the hub has been added. However, currently, this information can only be retrieved within UVC_OPEN. It is desired to add an API to retrieve device information before UVC_OPEN.

eg:

  esp_err_t libuvc_get_device_info(uvc_device_t *dev, usb_device_info_t *dev_info)
  {
      uvc_error_t ret;
      struct libusb_device_handle *usb_devh;
  
      ret = libusb_open(dev->usb_dev, &usb_devh);
      UVC_DEBUG("libusb_open() = %d", ret);
      if (ret != UVC_SUCCESS) {
          return ESP_FAIL;
      }
  
      uvc_camera_t *camera = (uvc_camera_t *)(usb_devh);
      RETURN_ON_ERROR( usb_host_device_info(camera->handle, dev_info) );
  
      libusb_close(usb_devh);
      return ESP_OK;
  } 

[tore-espressif]

@lijunru-hub Sorry for the late reply.

Draft implementation is here a639a34

Compared to your proposal, it is a little different: It accepts a uvc_device_handle_t , so the UVC device must be already opened. Does this solve your problem?

[lijunru-hub]

I think before uvc_open to get the hardware's info is better. Like use the uvc_device_t handle

[tore-espressif]

I think before uvc_open to get the hardware's info is better. Like use the uvc_device_t handle

Thank you for the feedback, I understand now. Implemented according to your suggestion in 83cf701