cec-ioc-dqevent.rst (7920B)
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: CEC 3 4.. _CEC_DQEVENT: 5 6***************** 7ioctl CEC_DQEVENT 8***************** 9 10Name 11==== 12 13CEC_DQEVENT - Dequeue a CEC event 14 15Synopsis 16======== 17 18.. c:macro:: CEC_DQEVENT 19 20``int ioctl(int fd, CEC_DQEVENT, struct cec_event *argp)`` 21 22Arguments 23========= 24 25``fd`` 26 File descriptor returned by :c:func:`open()`. 27 28``argp`` 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{13.2cm}| 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 * - __u16 67 - ``have_conn_info`` 68 - If non-zero, then HDMI connector information is available. 69 This field is only valid if ``CEC_CAP_CONNECTOR_INFO`` is set. If that 70 capability is set and ``have_conn_info`` is zero, then that indicates 71 that the HDMI connector device is not instantiated, either because 72 the HDMI driver is still configuring the device or because the HDMI 73 device was unbound. 74 75.. c:type:: cec_event_lost_msgs 76 77.. tabularcolumns:: |p{1.0cm}|p{2.0cm}|p{14.3cm}| 78 79.. flat-table:: struct cec_event_lost_msgs 80 :header-rows: 0 81 :stub-columns: 0 82 :widths: 1 1 16 83 84 * - __u32 85 - ``lost_msgs`` 86 - Set to the number of lost messages since the filehandle was opened 87 or since the last time this event was dequeued for this 88 filehandle. The messages lost are the oldest messages. So when a 89 new message arrives and there is no more room, then the oldest 90 message is discarded to make room for the new one. The internal 91 size of the message queue guarantees that all messages received in 92 the last two seconds will be stored. Since messages should be 93 replied to within a second according to the CEC specification, 94 this is more than enough. 95 96.. tabularcolumns:: |p{1.0cm}|p{4.4cm}|p{2.5cm}|p{9.2cm}| 97 98.. c:type:: cec_event 99 100.. flat-table:: struct cec_event 101 :header-rows: 0 102 :stub-columns: 0 103 :widths: 1 1 8 104 105 * - __u64 106 - ``ts`` 107 - Timestamp of the event in ns. 108 109 The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock. 110 111 To access the same clock from userspace use :c:func:`clock_gettime`. 112 * - __u32 113 - ``event`` 114 - The CEC event type, see :ref:`cec-events`. 115 * - __u32 116 - ``flags`` 117 - Event flags, see :ref:`cec-event-flags`. 118 * - union { 119 - (anonymous) 120 * - struct cec_event_state_change 121 - ``state_change`` 122 - The new adapter state as sent by the :ref:`CEC_EVENT_STATE_CHANGE <CEC-EVENT-STATE-CHANGE>` 123 event. 124 * - struct cec_event_lost_msgs 125 - ``lost_msgs`` 126 - The number of lost messages as sent by the :ref:`CEC_EVENT_LOST_MSGS <CEC-EVENT-LOST-MSGS>` 127 event. 128 * - } 129 - 130 131.. tabularcolumns:: |p{5.6cm}|p{0.9cm}|p{10.8cm}| 132 133.. _cec-events: 134 135.. flat-table:: CEC Events Types 136 :header-rows: 0 137 :stub-columns: 0 138 :widths: 3 1 16 139 140 * .. _`CEC-EVENT-STATE-CHANGE`: 141 142 - ``CEC_EVENT_STATE_CHANGE`` 143 - 1 144 - Generated when the CEC Adapter's state changes. When open() is 145 called an initial event will be generated for that filehandle with 146 the CEC Adapter's state at that time. 147 * .. _`CEC-EVENT-LOST-MSGS`: 148 149 - ``CEC_EVENT_LOST_MSGS`` 150 - 2 151 - Generated if one or more CEC messages were lost because the 152 application didn't dequeue CEC messages fast enough. 153 * .. _`CEC-EVENT-PIN-CEC-LOW`: 154 155 - ``CEC_EVENT_PIN_CEC_LOW`` 156 - 3 157 - Generated if the CEC pin goes from a high voltage to a low voltage. 158 Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN`` 159 capability set. 160 * .. _`CEC-EVENT-PIN-CEC-HIGH`: 161 162 - ``CEC_EVENT_PIN_CEC_HIGH`` 163 - 4 164 - Generated if the CEC pin goes from a low voltage to a high voltage. 165 Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN`` 166 capability set. 167 * .. _`CEC-EVENT-PIN-HPD-LOW`: 168 169 - ``CEC_EVENT_PIN_HPD_LOW`` 170 - 5 171 - Generated if the HPD pin goes from a high voltage to a low voltage. 172 Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN`` 173 capability set. When open() is called, the HPD pin can be read and 174 if the HPD is low, then an initial event will be generated for that 175 filehandle. 176 * .. _`CEC-EVENT-PIN-HPD-HIGH`: 177 178 - ``CEC_EVENT_PIN_HPD_HIGH`` 179 - 6 180 - Generated if the HPD pin goes from a low voltage to a high voltage. 181 Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN`` 182 capability set. When open() is called, the HPD pin can be read and 183 if the HPD is high, then an initial event will be generated for that 184 filehandle. 185 * .. _`CEC-EVENT-PIN-5V-LOW`: 186 187 - ``CEC_EVENT_PIN_5V_LOW`` 188 - 6 189 - Generated if the 5V pin goes from a high voltage to a low voltage. 190 Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN`` 191 capability set. When open() is called, the 5V pin can be read and 192 if the 5V is low, then an initial event will be generated for that 193 filehandle. 194 * .. _`CEC-EVENT-PIN-5V-HIGH`: 195 196 - ``CEC_EVENT_PIN_5V_HIGH`` 197 - 7 198 - Generated if the 5V pin goes from a low voltage to a high voltage. 199 Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN`` 200 capability set. When open() is called, the 5V pin can be read and 201 if the 5V is high, then an initial event will be generated for that 202 filehandle. 203 204.. tabularcolumns:: |p{6.0cm}|p{0.6cm}|p{10.7cm}| 205 206.. _cec-event-flags: 207 208.. flat-table:: CEC Event Flags 209 :header-rows: 0 210 :stub-columns: 0 211 :widths: 3 1 8 212 213 * .. _`CEC-EVENT-FL-INITIAL-STATE`: 214 215 - ``CEC_EVENT_FL_INITIAL_STATE`` 216 - 1 217 - Set for the initial events that are generated when the device is 218 opened. See the table above for which events do this. This allows 219 applications to learn the initial state of the CEC adapter at 220 open() time. 221 * .. _`CEC-EVENT-FL-DROPPED-EVENTS`: 222 223 - ``CEC_EVENT_FL_DROPPED_EVENTS`` 224 - 2 225 - Set if one or more events of the given event type have been dropped. 226 This is an indication that the application cannot keep up. 227 228 229Return Value 230============ 231 232On success 0 is returned, on error -1 and the ``errno`` variable is set 233appropriately. The generic error codes are described at the 234:ref:`Generic Error Codes <gen-errors>` chapter. 235 236The :ref:`ioctl CEC_DQEVENT <CEC_DQEVENT>` can return the following 237error codes: 238 239EAGAIN 240 This is returned when the filehandle is in non-blocking mode and there 241 are no pending events. 242 243ERESTARTSYS 244 An interrupt (e.g. Ctrl-C) arrived while in blocking mode waiting for 245 events to arrive.