ioctl MEDIA_IOC_G_TOPOLOGY &manvol; MEDIA_IOC_G_TOPOLOGY Enumerate the graph topology and graph element properties int ioctl int fd int request struct media_v2_topology *argp fd File descriptor returned by open(). request MEDIA_IOC_G_TOPOLOGY argp The typical usage of this ioctl is to call it twice. On the first call, the structure defined at &media-v2-topology; should be zeroed. At return, if no errors happen, this ioctl will return the topology_version and the total number of entities, interfaces, pads and links. Before the second call, the userspace should allocate arrays to store the graph elements that are desired, putting the pointers to them at the ptr_entities, ptr_interfaces, ptr_links and/or ptr_pads, keeping the other values untouched. If the topology_version remains the same, the ioctl should fill the desired arrays with the media graph elements. __u64 topology_version Version of the media graph topology. When the graph is created, this field starts with zero. Every time a graph element is added or removed, this field is incremented. __u64 num_entities Number of entities in the graph __u64 ptr_entities A pointer to a memory area where the entities array will be stored, converted to a 64-bits integer. It can be zero. if zero, the ioctl won't store the entities. It will just update num_entities __u64 num_interfaces Number of interfaces in the graph __u64 ptr_interfaces A pointer to a memory area where the interfaces array will be stored, converted to a 64-bits integer. It can be zero. if zero, the ioctl won't store the interfaces. It will just update num_interfaces __u64 num_pads Total number of pads in the graph __u64 ptr_pads A pointer to a memory area where the pads array will be stored, converted to a 64-bits integer. It can be zero. if zero, the ioctl won't store the pads. It will just update num_pads __u64 num_links Total number of data and interface links in the graph __u64 ptr_links A pointer to a memory area where the links array will be stored, converted to a 64-bits integer. It can be zero. if zero, the ioctl won't store the links. It will just update num_links __u32 id Unique ID for the entity. char name[64] Entity name as an UTF-8 NULL-terminated string. __u32 function Entity main function, see for details. __u32 reserved[12] Reserved for future extensions. Drivers and applications must set this array to zero. __u32 id Unique ID for the interface. __u32 intf_type Interface type, see for details. __u32 flags Interface flags. Currently unused. __u32 reserved[9] Reserved for future extensions. Drivers and applications must set this array to zero. struct media_v2_intf_devnode devnode Used only for device node interfaces. See for details.. __u32 major Device node major number. __u32 minor Device node minor number. __u32 id Unique ID for the pad. __u32 entity_id Unique ID for the entity where this pad belongs. __u32 flags Pad flags, see for more details. __u32 reserved[9] Reserved for future extensions. Drivers and applications must set this array to zero. __u32 id Unique ID for the pad. __u32 source_id On pad to pad links: unique ID for the source pad. On interface to entity links: unique ID for the interface. __u32 sink_id On pad to pad links: unique ID for the sink pad. On interface to entity links: unique ID for the entity. __u32 flags Link flags, see for more details. __u32 reserved[5] Reserved for future extensions. Drivers and applications must set this array to zero. &return-value; ENOSPC This is returned when either one or more of the num_entities, num_interfaces, num_links or num_pads are non-zero and are smaller than the actual number of elements inside the graph. This may happen if the topology_version changed when compared to the last time this ioctl was called. Userspace should usually free the area for the pointers, zero the struct elements and call this ioctl again.