1.. -*- coding: utf-8; mode: rst -*-
2
3.. _CEC_DQEVENT:
4
5*****************
6ioctl CEC_DQEVENT
7*****************
8
9Name
10====
11
12CEC_DQEVENT - Dequeue a CEC event
13
14
15Synopsis
16========
17
18.. c:function:: int ioctl( int fd, CEC_DQEVENT, struct cec_event *argp )
19    :name: CEC_DQEVENT
20
21Arguments
22=========
23
24``fd``
25    File descriptor returned by :c:func:`open() <cec-open>`.
26
27``argp``
28
29
30Description
31===========
32
33CEC devices can send asynchronous events. These can be retrieved by
34calling :c:func:`CEC_DQEVENT`. If the file descriptor is in
35non-blocking mode and no event is pending, then it will return -1 and
36set errno to the ``EAGAIN`` error code.
37
38The internal event queues are per-filehandle and per-event type. If
39there is no more room in a queue then the last event is overwritten with
40the new one. This means that intermediate results can be thrown away but
41that the latest event is always available. This also means that is it
42possible to read two successive events that have the same value (e.g.
43two :ref:`CEC_EVENT_STATE_CHANGE <CEC-EVENT-STATE-CHANGE>` events with
44the same state). In that case the intermediate state changes were lost but
45it is guaranteed that the state did change in between the two events.
46
47.. tabularcolumns:: |p{1.2cm}|p{2.9cm}|p{13.4cm}|
48
49.. c:type:: cec_event_state_change
50
51.. flat-table:: struct cec_event_state_change
52    :header-rows:  0
53    :stub-columns: 0
54    :widths:       1 1 8
55
56    * - __u16
57      - ``phys_addr``
58      - The current physical address. This is ``CEC_PHYS_ADDR_INVALID`` if no
59        valid physical address is set.
60    * - __u16
61      - ``log_addr_mask``
62      - The current set of claimed logical addresses. This is 0 if no logical
63        addresses are claimed or if ``phys_addr`` is ``CEC_PHYS_ADDR_INVALID``.
64	If bit 15 is set (``1 << CEC_LOG_ADDR_UNREGISTERED``) then this device
65	has the unregistered logical address. In that case all other bits are 0.
66
67
68.. c:type:: cec_event_lost_msgs
69
70.. tabularcolumns:: |p{1.0cm}|p{2.0cm}|p{14.5cm}|
71
72.. flat-table:: struct cec_event_lost_msgs
73    :header-rows:  0
74    :stub-columns: 0
75    :widths:       1 1 16
76
77    * - __u32
78      - ``lost_msgs``
79      - Set to the number of lost messages since the filehandle was opened
80	or since the last time this event was dequeued for this
81	filehandle. The messages lost are the oldest messages. So when a
82	new message arrives and there is no more room, then the oldest
83	message is discarded to make room for the new one. The internal
84	size of the message queue guarantees that all messages received in
85	the last two seconds will be stored. Since messages should be
86	replied to within a second according to the CEC specification,
87	this is more than enough.
88
89
90.. tabularcolumns:: |p{1.0cm}|p{4.4cm}|p{2.5cm}|p{9.6cm}|
91
92.. c:type:: cec_event
93
94.. flat-table:: struct cec_event
95    :header-rows:  0
96    :stub-columns: 0
97    :widths:       1 1 1 8
98
99    * - __u64
100      - ``ts``
101      - :cspan:`1`\ Timestamp of the event in ns.
102
103	The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock.
104
105	To access the same clock from userspace use :c:func:`clock_gettime`.
106    * - __u32
107      - ``event``
108      - :cspan:`1` The CEC event type, see :ref:`cec-events`.
109    * - __u32
110      - ``flags``
111      - :cspan:`1` Event flags, see :ref:`cec-event-flags`.
112    * - union
113      - (anonymous)
114      -
115      -
116    * -
117      - struct cec_event_state_change
118      - ``state_change``
119      - The new adapter state as sent by the :ref:`CEC_EVENT_STATE_CHANGE <CEC-EVENT-STATE-CHANGE>`
120	event.
121    * -
122      - struct cec_event_lost_msgs
123      - ``lost_msgs``
124      - The number of lost messages as sent by the :ref:`CEC_EVENT_LOST_MSGS <CEC-EVENT-LOST-MSGS>`
125	event.
126
127
128.. tabularcolumns:: |p{5.6cm}|p{0.9cm}|p{11.0cm}|
129
130.. _cec-events:
131
132.. flat-table:: CEC Events Types
133    :header-rows:  0
134    :stub-columns: 0
135    :widths:       3 1 16
136
137    * .. _`CEC-EVENT-STATE-CHANGE`:
138
139      - ``CEC_EVENT_STATE_CHANGE``
140      - 1
141      - Generated when the CEC Adapter's state changes. When open() is
142	called an initial event will be generated for that filehandle with
143	the CEC Adapter's state at that time.
144    * .. _`CEC-EVENT-LOST-MSGS`:
145
146      - ``CEC_EVENT_LOST_MSGS``
147      - 2
148      - Generated if one or more CEC messages were lost because the
149	application didn't dequeue CEC messages fast enough.
150    * .. _`CEC-EVENT-PIN-CEC-LOW`:
151
152      - ``CEC_EVENT_PIN_CEC_LOW``
153      - 3
154      - Generated if the CEC pin goes from a high voltage to a low voltage.
155        Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN``
156	capability set.
157    * .. _`CEC-EVENT-PIN-CEC-HIGH`:
158
159      - ``CEC_EVENT_PIN_CEC_HIGH``
160      - 4
161      - Generated if the CEC pin goes from a low voltage to a high voltage.
162        Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN``
163	capability set.
164    * .. _`CEC-EVENT-PIN-HPD-LOW`:
165
166      - ``CEC_EVENT_PIN_HPD_LOW``
167      - 5
168      - Generated if the HPD pin goes from a high voltage to a low voltage.
169	Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN``
170	capability set. When open() is called, the HPD pin can be read and
171	if the HPD is low, then an initial event will be generated for that
172	filehandle.
173    * .. _`CEC-EVENT-PIN-HPD-HIGH`:
174
175      - ``CEC_EVENT_PIN_HPD_HIGH``
176      - 6
177      - Generated if the HPD pin goes from a low voltage to a high voltage.
178	Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN``
179	capability set. When open() is called, the HPD pin can be read and
180	if the HPD is high, then an initial event will be generated for that
181	filehandle.
182    * .. _`CEC-EVENT-PIN-5V-LOW`:
183
184      - ``CEC_EVENT_PIN_5V_LOW``
185      - 6
186      - Generated if the 5V pin goes from a high voltage to a low voltage.
187	Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN``
188	capability set. When open() is called, the 5V pin can be read and
189	if the 5V is low, then an initial event will be generated for that
190	filehandle.
191    * .. _`CEC-EVENT-PIN-5V-HIGH`:
192
193      - ``CEC_EVENT_PIN_5V_HIGH``
194      - 7
195      - Generated if the 5V pin goes from a low voltage to a high voltage.
196	Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN``
197	capability set. When open() is called, the 5V pin can be read and
198	if the 5V is high, then an initial event will be generated for that
199	filehandle.
200
201
202.. tabularcolumns:: |p{6.0cm}|p{0.6cm}|p{10.9cm}|
203
204.. _cec-event-flags:
205
206.. flat-table:: CEC Event Flags
207    :header-rows:  0
208    :stub-columns: 0
209    :widths:       3 1 8
210
211    * .. _`CEC-EVENT-FL-INITIAL-STATE`:
212
213      - ``CEC_EVENT_FL_INITIAL_STATE``
214      - 1
215      - Set for the initial events that are generated when the device is
216	opened. See the table above for which events do this. This allows
217	applications to learn the initial state of the CEC adapter at
218	open() time.
219    * .. _`CEC-EVENT-FL-DROPPED-EVENTS`:
220
221      - ``CEC_EVENT_FL_DROPPED_EVENTS``
222      - 2
223      - Set if one or more events of the given event type have been dropped.
224        This is an indication that the application cannot keep up.
225
226
227
228Return Value
229============
230
231On success 0 is returned, on error -1 and the ``errno`` variable is set
232appropriately. The generic error codes are described at the
233:ref:`Generic Error Codes <gen-errors>` chapter.
234
235The :ref:`ioctl CEC_DQEVENT <CEC_DQEVENT>` can return the following
236error codes:
237
238EAGAIN
239    This is returned when the filehandle is in non-blocking mode and there
240    are no pending events.
241
242ERESTARTSYS
243    An interrupt (e.g. Ctrl-C) arrived while in blocking mode waiting for
244    events to arrive.
245