ioctl CEC_DQEVENT
&manvol;
CEC_DQEVENTDequeue a CEC eventint ioctlint fdint requeststruct cec_event *argpArgumentsfdFile descriptor returned by
open().requestCEC_DQEVENTargpDescription
Note: this documents the proposed CEC API. This API is not yet finalized and
is currently only available as a staging kernel module.
CEC devices can send asynchronous events. These can be retrieved by calling
the CEC_DQEVENT ioctl. If the file descriptor is in non-blocking
mode and no event is pending, then it will return -1 and set errno to the &EAGAIN;.The internal event queues are per-filehandle and per-event type. If there is
no more room in a queue then the last event is overwritten with the new one. This
means that intermediate results can be thrown away but that the latest event is always
available. This also means that is it possible to read two successive events that have
the same value (e.g. two CEC_EVENT_STATE_CHANGE events with the same state). In that
case the intermediate state changes were lost but it is guaranteed that the state
did change in between the two events.
struct cec_event_state_change
&cs-str;
__u16phys_addrThe current physical address.__u16log_addr_maskThe current set of claimed logical addresses.
struct cec_event_lost_msgs
&cs-str;
__u32lost_msgsSet to the number of lost messages since the filehandle
was opened or since the last time this event was dequeued for
this filehandle. The messages lost are the oldest messages. So
when a new message arrives and there is no more room, then the
oldest message is discarded to make room for the new one. The
internal size of the message queue guarantees that all messages
received in the last two seconds will be stored. Since messages
should be replied to within a second according to the CEC
specification, this is more than enough.
struct cec_event
&cs-str;
__u64tsTimestamp of the event in ns.__u32eventThe CEC event type, see .__u32flagsEvent flags, see .union(anonymous)struct cec_event_state_changestate_changeThe new adapter state as sent by the CEC_EVENT_STATE_CHANGE
event.struct cec_event_lost_msgslost_msgsThe number of lost messages as sent by the CEC_EVENT_LOST_MSGS
event.
CEC Events Types
&cs-def;
CEC_EVENT_STATE_CHANGE1Generated when the CEC Adapter's state changes. When open() is
called an initial event will be generated for that filehandle with the
CEC Adapter's state at that time.
CEC_EVENT_LOST_MSGS2Generated if one or more CEC messages were lost because the
application didn't dequeue CEC messages fast enough.
CEC Event Flags
&cs-def;
CEC_EVENT_FL_INITIAL_VALUE1Set for the initial events that are generated when the device is
opened. See the table above for which events do this. This allows
applications to learn the initial state of the CEC adapter at open()
time.