Hi Folks. I am working on a system based around the Intel Apollo Lake with an IPU4. The system is having a configuration with a number of subdevices. Going from v4l-subdev0 to v4-subdev10. Running gst-device-monitor-1.0 results in a number of errors like. GStreamer-CRITICAL **: 13:27:36.763: gst_element_message_full_with_details: assertion 'GST_IS_ELEMENT (element)' failed The reason is because a VIDIOC_QUERYCAP on the subdevice fails. Looking at the documentation https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/vidioc-querycap.html it states that "All V4L2 devices support the VIDIOC_QUERYCAP ioctl" On the other hand VIDIOC_QUERYCAP is not part of the subset mentioned in documentation for V4L2 sub-device. https://www.kernel.org/doc/html/latest/driver-api/media/v4l2-subdev.html So is I correct that gstreamer has a bug in gst-device-monitor-1.0, and it should not try to use the VIDIOC_QUERYCAP ioctl for a sub-device? It could be that gstreamer should just skip the sub-device. Regards Claus Stovgaard
