€•¬)      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ5/translations/zh_CN/userspace-api/media/v4l/dev-event”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ5/translations/zh_TW/userspace-api/media/v4l/dev-event”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ5/translations/it_IT/userspace-api/media/v4l/dev-event”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ5/translations/ja_JP/userspace-api/media/v4l/dev-event”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ5/translations/ko_KR/userspace-api/media/v4l/dev-event”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ5/translations/sp_SP/userspace-api/media/v4l/dev-event”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ8SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later”h]”hŒ8SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later”…””}”hh£sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1h¡hhhžhhŸŒO/var/lib/git/docbuild/linux/Documentation/userspace-api/media/v4l/dev-event.rst”h KubhŒtarget”“”)”}”(hŒ
.. _event:”h]”h}”(h]”h ]”h"]”h$]”h&]”Œrefid”Œevent”uh1h´h KhhhžhhŸh³ubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒEvent Interface”h]”hŒEvent Interface”…””}”(hhÉhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÇhhÄhžhhŸh³h KubhŒ	paragraph”“”)”}”(hX  The V4L2 event interface provides a means for a user to get immediately
notified on certain conditions taking place on a device. This might
include start of frame or loss of signal events, for example. Changes in
the value or state of a V4L2 control can also be reported through
events.”h]”hX  The V4L2 event interface provides a means for a user to get immediately
notified on certain conditions taking place on a device. This might
include start of frame or loss of signal events, for example. Changes in
the value or state of a V4L2 control can also be reported through
events.”…””}”(hhÙhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh³h K	hhÄhžhubhØ)”}”(hX˜  To receive events, the events the user is interested in first must be
subscribed using the
:ref:`VIDIOC_SUBSCRIBE_EVENT` ioctl. Once
an event is subscribed, the events of subscribed types are dequeueable
using the :ref:`VIDIOC_DQEVENT` ioctl. Events may be
unsubscribed using VIDIOC_UNSUBSCRIBE_EVENT ioctl. The special event
type V4L2_EVENT_ALL may be used to unsubscribe all the events the
driver supports.”h]”(hŒ[To receive events, the events the user is interested in first must be
subscribed using the
”…””}”(hhçhžhhŸNh Nubh)”}”(hŒ:ref:`VIDIOC_SUBSCRIBE_EVENT`”h]”hŒinline”“”)”}”(hhñh]”hŒVIDIOC_SUBSCRIBE_EVENT”…””}”(hhõhžhhŸNh Nubah}”(h]”h ]”(Œxref”Œstd”Œstd-ref”eh"]”h$]”h&]”uh1hóhhïubah}”(h]”h ]”h"]”h$]”h&]”Œrefdoc”Œ!userspace-api/media/v4l/dev-event”Œ	refdomain”j   Œreftype”Œref”Œrefexplicit”‰Œrefwarn”ˆŒ	reftarget”Œvidioc_subscribe_event”uh1hhŸh³h KhhçubhŒ^ ioctl. Once
an event is subscribed, the events of subscribed types are dequeueable
using the ”…””}”(hhçhžhhŸNh Nubh)”}”(hŒ:ref:`VIDIOC_DQEVENT`”h]”hô)”}”(hj  h]”hŒVIDIOC_DQEVENT”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”(hÿŒstd”Œstd-ref”eh"]”h$]”h&]”uh1hóhj  ubah}”(h]”h ]”h"]”h$]”h&]”Œrefdoc”j  Œ	refdomain”j&  Œreftype”Œref”Œrefexplicit”‰Œrefwarn”ˆj  Œvidioc_dqevent”uh1hhŸh³h KhhçubhŒ­ ioctl. Events may be
unsubscribed using VIDIOC_UNSUBSCRIBE_EVENT ioctl. The special event
type V4L2_EVENT_ALL may be used to unsubscribe all the events the
driver supports.”…””}”(hhçhžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh³h KhhÄhžhubhØ)”}”(hŒ’The event subscriptions and event queues are specific to file handles.
Subscribing an event on one file handle does not affect other file
handles.”h]”hŒ’The event subscriptions and event queues are specific to file handles.
Subscribing an event on one file handle does not affect other file
handles.”…””}”(hjB  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh³h KhhÄhžhubhØ)”}”(hŒÅThe information on dequeueable events is obtained by using select or
poll system calls on video devices. The V4L2 events use POLLPRI events
on poll system call and exceptions on select system call.”h]”hŒÅThe information on dequeueable events is obtained by using select or
poll system calls on video devices. The V4L2 events use POLLPRI events
on poll system call and exceptions on select system call.”…””}”(hjP  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh³h KhhÄhžhubhØ)”}”(hŒPStarting with kernel 3.1 certain guarantees can be given with regards to
events:”h]”hŒPStarting with kernel 3.1 certain guarantees can be given with regards to
events:”…””}”(hj^  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh³h K hhÄhžhubhŒenumerated_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒ˜Each subscribed event has its own internal dedicated event queue.
This means that flooding of one event type will not interfere with
other event types.
”h]”hØ)”}”(hŒ—Each subscribed event has its own internal dedicated event queue.
This means that flooding of one event type will not interfere with
other event types.”h]”hŒ—Each subscribed event has its own internal dedicated event queue.
This means that flooding of one event type will not interfere with
other event types.”…””}”(hjw  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh³h K#hjs  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jq  hjn  hžhhŸh³h Nubjr  )”}”(hŒIf the internal event queue for a particular subscribed event becomes
full, then the oldest event in that queue will be dropped.
”h]”hØ)”}”(hŒ€If the internal event queue for a particular subscribed event becomes
full, then the oldest event in that queue will be dropped.”h]”hŒ€If the internal event queue for a particular subscribed event becomes
full, then the oldest event in that queue will be dropped.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh³h K'hj‹  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jq  hjn  hžhhŸh³h Nubjr  )”}”(hXƒ  Where applicable, certain event types can ensure that the payload of
the oldest event that is about to be dropped will be merged with the
payload of the next oldest event. Thus ensuring that no information
is lost, but only an intermediate step leading up to that
information. See the documentation for the event you want to
subscribe to whether this is applicable for that event or not.”h]”hØ)”}”(hXƒ  Where applicable, certain event types can ensure that the payload of
the oldest event that is about to be dropped will be merged with the
payload of the next oldest event. Thus ensuring that no information
is lost, but only an intermediate step leading up to that
information. See the documentation for the event you want to
subscribe to whether this is applicable for that event or not.”h]”hXƒ  Where applicable, certain event types can ensure that the payload of
the oldest event that is about to be dropped will be merged with the
payload of the next oldest event. Thus ensuring that no information
is lost, but only an intermediate step leading up to that
information. See the documentation for the event you want to
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id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”hŒsystem_message”“”)”}”(hhh]”hØ)”}”(hhh]”hŒ+Hyperlink target "event" is not referenced.”…””}”hj`  sbah}”(h]”h ]”h"]”h$]”h&]”uh1h×hj]  ubah}”(h]”h ]”h"]”h$]”h&]”Œlevel”KŒtype”ŒINFO”Œsource”h³Œline”Kuh1j[  ubaŒtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.