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54f38fcae5
Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").
As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.
Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
101 lines
3.6 KiB
ReStructuredText
101 lines
3.6 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
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.. document under the terms of the GNU Free Documentation License,
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.. Version 1.1 or any later version published by the Free Software
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.. Foundation, with no Invariant Sections, no Front-Cover Texts
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.. and no Back-Cover Texts. A copy of the license is included at
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.. Documentation/userspace-api/media/fdl-appendix.rst.
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..
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.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
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.. _CEC_ADAP_PHYS_ADDR:
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.. _CEC_ADAP_G_PHYS_ADDR:
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.. _CEC_ADAP_S_PHYS_ADDR:
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****************************************************
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ioctls CEC_ADAP_G_PHYS_ADDR and CEC_ADAP_S_PHYS_ADDR
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****************************************************
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Name
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====
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CEC_ADAP_G_PHYS_ADDR, CEC_ADAP_S_PHYS_ADDR - Get or set the physical address
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Synopsis
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========
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.. c:function:: int ioctl( int fd, CEC_ADAP_G_PHYS_ADDR, __u16 *argp )
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:name: CEC_ADAP_G_PHYS_ADDR
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.. c:function:: int ioctl( int fd, CEC_ADAP_S_PHYS_ADDR, __u16 *argp )
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:name: CEC_ADAP_S_PHYS_ADDR
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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() <cec-open>`.
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``argp``
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Pointer to the CEC address.
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Description
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===========
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To query the current physical address applications call
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:ref:`ioctl CEC_ADAP_G_PHYS_ADDR <CEC_ADAP_G_PHYS_ADDR>` with a pointer to a __u16 where the
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driver stores the physical address.
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To set a new physical address applications store the physical address in
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a __u16 and call :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` with a pointer to
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this integer. The :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` is only available if
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``CEC_CAP_PHYS_ADDR`` is set (the ``ENOTTY`` error code will be returned
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otherwise). The :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` can only be called
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by a file descriptor in initiator mode (see :ref:`CEC_S_MODE`), if not
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the ``EBUSY`` error code will be returned.
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To clear an existing physical address use ``CEC_PHYS_ADDR_INVALID``.
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The adapter will go to the unconfigured state.
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If logical address types have been defined (see :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`),
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then this ioctl will block until all
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requested logical addresses have been claimed. If the file descriptor is in non-blocking mode
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then it will not wait for the logical addresses to be claimed, instead it just returns 0.
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A :ref:`CEC_EVENT_STATE_CHANGE <CEC-EVENT-STATE-CHANGE>` event is sent when the physical address
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changes.
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The physical address is a 16-bit number where each group of 4 bits
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represent a digit of the physical address a.b.c.d where the most
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significant 4 bits represent 'a'. The CEC root device (usually the TV)
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has address 0.0.0.0. Every device that is hooked up to an input of the
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TV has address a.0.0.0 (where 'a' is ≥ 1), devices hooked up to those in
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turn have addresses a.b.0.0, etc. So a topology of up to 5 devices deep
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is supported. The physical address a device shall use is stored in the
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EDID of the sink.
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For example, the EDID for each HDMI input of the TV will have a
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different physical address of the form a.0.0.0 that the sources will
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read out and use as their physical address.
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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_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` can return the following
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error codes:
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ENOTTY
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The ``CEC_CAP_PHYS_ADDR`` capability wasn't set, so this ioctl is not supported.
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EBUSY
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Another filehandle is in exclusive follower or initiator mode, or the filehandle
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is in mode ``CEC_MODE_NO_INITIATOR``.
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EINVAL
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The physical address is malformed.
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