295 lines
11 KiB
ReStructuredText
295 lines
11 KiB
ReStructuredText
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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: CEC
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.. _CEC_MODE:
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.. _CEC_G_MODE:
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.. _CEC_S_MODE:
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********************************
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ioctls CEC_G_MODE and CEC_S_MODE
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********************************
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CEC_G_MODE, CEC_S_MODE - Get or set exclusive use of the CEC adapter
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Synopsis
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========
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.. c:macro:: CEC_G_MODE
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``int ioctl(int fd, CEC_G_MODE, __u32 *argp)``
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.. c:macro:: CEC_S_MODE
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``int ioctl(int fd, CEC_S_MODE, __u32 *argp)``
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Arguments
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=========
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``fd``
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File descriptor returned by :c:func:`open()`.
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``argp``
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Pointer to CEC mode.
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Description
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===========
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By default any filehandle can use :ref:`CEC_TRANSMIT`, but in order to prevent
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applications from stepping on each others toes it must be possible to
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obtain exclusive access to the CEC adapter. This ioctl sets the
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filehandle to initiator and/or follower mode which can be exclusive
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depending on the chosen mode. The initiator is the filehandle that is
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used to initiate messages, i.e. it commands other CEC devices. The
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follower is the filehandle that receives messages sent to the CEC
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adapter and processes them. The same filehandle can be both initiator
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and follower, or this role can be taken by two different filehandles.
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When a CEC message is received, then the CEC framework will decide how
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it will be processed. If the message is a reply to an earlier
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transmitted message, then the reply is sent back to the filehandle that
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is waiting for it. In addition the CEC framework will process it.
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If the message is not a reply, then the CEC framework will process it
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first. If there is no follower, then the message is just discarded and a
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feature abort is sent back to the initiator if the framework couldn't
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process it. If there is a follower, then the message is passed on to the
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follower who will use :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>` to dequeue
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the new message. The framework expects the follower to make the right
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decisions.
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The CEC framework will process core messages unless requested otherwise
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by the follower. The follower can enable the passthrough mode. In that
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case, the CEC framework will pass on most core messages without
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processing them and the follower will have to implement those messages.
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There are some messages that the core will always process, regardless of
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the passthrough mode. See :ref:`cec-core-processing` for details.
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If there is no initiator, then any CEC filehandle can use
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:ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>`. If there is an exclusive
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initiator then only that initiator can call
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:ref:`CEC_TRANSMIT`. The follower can of course
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always call :ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>`.
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Available initiator modes are:
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.. tabularcolumns:: |p{5.6cm}|p{0.9cm}|p{10.8cm}|
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.. _cec-mode-initiator_e:
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.. flat-table:: Initiator Modes
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 16
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* .. _`CEC-MODE-NO-INITIATOR`:
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- ``CEC_MODE_NO_INITIATOR``
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- 0x0
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- This is not an initiator, i.e. it cannot transmit CEC messages or
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make any other changes to the CEC adapter.
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* .. _`CEC-MODE-INITIATOR`:
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- ``CEC_MODE_INITIATOR``
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- 0x1
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- This is an initiator (the default when the device is opened) and
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it can transmit CEC messages and make changes to the CEC adapter,
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unless there is an exclusive initiator.
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* .. _`CEC-MODE-EXCL-INITIATOR`:
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- ``CEC_MODE_EXCL_INITIATOR``
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- 0x2
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- This is an exclusive initiator and this file descriptor is the
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only one that can transmit CEC messages and make changes to the
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CEC adapter. If someone else is already the exclusive initiator
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then an attempt to become one will return the ``EBUSY`` error code
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error.
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Available follower modes are:
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.. tabularcolumns:: |p{6.6cm}|p{0.9cm}|p{9.8cm}|
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.. _cec-mode-follower_e:
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.. cssclass:: longtable
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.. flat-table:: Follower Modes
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 16
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* .. _`CEC-MODE-NO-FOLLOWER`:
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- ``CEC_MODE_NO_FOLLOWER``
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- 0x00
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- This is not a follower (the default when the device is opened).
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* .. _`CEC-MODE-FOLLOWER`:
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- ``CEC_MODE_FOLLOWER``
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- 0x10
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- This is a follower and it will receive CEC messages unless there
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is an exclusive follower. You cannot become a follower if
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:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`
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was specified, the ``EINVAL`` error code is returned in that case.
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* .. _`CEC-MODE-EXCL-FOLLOWER`:
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- ``CEC_MODE_EXCL_FOLLOWER``
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- 0x20
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- This is an exclusive follower and only this file descriptor will
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receive CEC messages for processing. If someone else is already
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the exclusive follower then an attempt to become one will return
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the ``EBUSY`` error code. You cannot become a follower if
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:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`
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was specified, the ``EINVAL`` error code is returned in that case.
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* .. _`CEC-MODE-EXCL-FOLLOWER-PASSTHRU`:
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- ``CEC_MODE_EXCL_FOLLOWER_PASSTHRU``
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- 0x30
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- This is an exclusive follower and only this file descriptor will
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receive CEC messages for processing. In addition it will put the
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CEC device into passthrough mode, allowing the exclusive follower
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to handle most core messages instead of relying on the CEC
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framework for that. If someone else is already the exclusive
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follower then an attempt to become one will return the ``EBUSY`` error
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code. You cannot become a follower if :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>`
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is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` was specified,
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the ``EINVAL`` error code is returned in that case.
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* .. _`CEC-MODE-MONITOR-PIN`:
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- ``CEC_MODE_MONITOR_PIN``
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- 0xd0
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- Put the file descriptor into pin monitoring mode. Can only be used in
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combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`,
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otherwise the ``EINVAL`` error code will be returned.
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This mode requires that the :ref:`CEC_CAP_MONITOR_PIN <CEC-CAP-MONITOR-PIN>`
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capability is set, otherwise the ``EINVAL`` error code is returned.
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While in pin monitoring mode this file descriptor can receive the
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``CEC_EVENT_PIN_CEC_LOW`` and ``CEC_EVENT_PIN_CEC_HIGH`` events to see the
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low-level CEC pin transitions. This is very useful for debugging.
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This mode is only allowed if the process has the ``CAP_NET_ADMIN``
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capability. If that is not set, then the ``EPERM`` error code is returned.
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* .. _`CEC-MODE-MONITOR`:
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- ``CEC_MODE_MONITOR``
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- 0xe0
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- Put the file descriptor into monitor mode. Can only be used in
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combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`,
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otherwise the ``EINVAL`` error code will be returned.
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In monitor mode all messages this CEC
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device transmits and all messages it receives (both broadcast
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messages and directed messages for one its logical addresses) will
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be reported. This is very useful for debugging. This is only
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allowed if the process has the ``CAP_NET_ADMIN`` capability. If
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that is not set, then the ``EPERM`` error code is returned.
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* .. _`CEC-MODE-MONITOR-ALL`:
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- ``CEC_MODE_MONITOR_ALL``
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- 0xf0
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- Put the file descriptor into 'monitor all' mode. Can only be used
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in combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise
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the ``EINVAL`` error code will be returned. In 'monitor all' mode all messages
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this CEC device transmits and all messages it receives, including
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directed messages for other CEC devices, will be reported. This is
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very useful for debugging, but not all devices support this. This
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mode requires that the :ref:`CEC_CAP_MONITOR_ALL <CEC-CAP-MONITOR-ALL>` capability is set,
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otherwise the ``EINVAL`` error code is returned. This is only allowed if
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the process has the ``CAP_NET_ADMIN`` capability. If that is not
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set, then the ``EPERM`` error code is returned.
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Core message processing details:
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.. tabularcolumns:: |p{6.6cm}|p{10.9cm}|
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.. _cec-core-processing:
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.. flat-table:: Core Message Processing
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 8
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* .. _`CEC-MSG-GET-CEC-VERSION`:
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- ``CEC_MSG_GET_CEC_VERSION``
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- The core will return the CEC version that was set with
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:ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`,
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except when in passthrough mode. In passthrough mode the core
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does nothing and this message has to be handled by a follower
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instead.
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* .. _`CEC-MSG-GIVE-DEVICE-VENDOR-ID`:
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- ``CEC_MSG_GIVE_DEVICE_VENDOR_ID``
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- The core will return the vendor ID that was set with
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:ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`,
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except when in passthrough mode. In passthrough mode the core
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does nothing and this message has to be handled by a follower
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instead.
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* .. _`CEC-MSG-ABORT`:
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- ``CEC_MSG_ABORT``
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- The core will return a Feature Abort message with reason
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'Feature Refused' as per the specification, except when in
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passthrough mode. In passthrough mode the core does nothing
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and this message has to be handled by a follower instead.
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* .. _`CEC-MSG-GIVE-PHYSICAL-ADDR`:
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- ``CEC_MSG_GIVE_PHYSICAL_ADDR``
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- The core will report the current physical address, except when
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in passthrough mode. In passthrough mode the core does nothing
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and this message has to be handled by a follower instead.
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* .. _`CEC-MSG-GIVE-OSD-NAME`:
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- ``CEC_MSG_GIVE_OSD_NAME``
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- The core will report the current OSD name that was set with
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:ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`,
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except when in passthrough mode. In passthrough mode the core
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does nothing and this message has to be handled by a follower
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instead.
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* .. _`CEC-MSG-GIVE-FEATURES`:
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- ``CEC_MSG_GIVE_FEATURES``
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- The core will do nothing if the CEC version is older than 2.0,
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otherwise it will report the current features that were set with
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:ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`,
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except when in passthrough mode. In passthrough mode the core
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does nothing (for any CEC version) and this message has to be handled
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by a follower instead.
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* .. _`CEC-MSG-USER-CONTROL-PRESSED`:
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- ``CEC_MSG_USER_CONTROL_PRESSED``
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- If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set and if
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:ref:`CEC_LOG_ADDRS_FL_ALLOW_RC_PASSTHRU <CEC-LOG-ADDRS-FL-ALLOW-RC-PASSTHRU>`
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is set, then generate a remote control key
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press. This message is always passed on to the follower(s).
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* .. _`CEC-MSG-USER-CONTROL-RELEASED`:
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- ``CEC_MSG_USER_CONTROL_RELEASED``
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- If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set and if
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:ref:`CEC_LOG_ADDRS_FL_ALLOW_RC_PASSTHRU <CEC-LOG-ADDRS-FL-ALLOW-RC-PASSTHRU>`
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is set, then generate a remote control key
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release. This message is always passed on to the follower(s).
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* .. _`CEC-MSG-REPORT-PHYSICAL-ADDR`:
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- ``CEC_MSG_REPORT_PHYSICAL_ADDR``
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- The CEC framework will make note of the reported physical address
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and then just pass the message on to the follower(s).
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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The :ref:`ioctl CEC_S_MODE <CEC_S_MODE>` can return the following
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error codes:
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EINVAL
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The requested mode is invalid.
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EPERM
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Monitor mode is requested, but the process does have the ``CAP_NET_ADMIN``
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capability.
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EBUSY
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Someone else is already an exclusive follower or initiator.
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