Commit e5208ed2 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab

[media] doc-rst: cec: update documentation

Update and expand the CEC documentation. Especially w.r.t. non-blocking
mode.
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent ef88f10e
......@@ -32,12 +32,12 @@ Arguments
Open flags. Access mode must be ``O_RDWR``.
When the ``O_NONBLOCK`` flag is given, the
:ref:`CEC_RECEIVE <CEC_RECEIVE>` ioctl will return the EAGAIN
error code when no message is available, and ioctls
:ref:`CEC_TRANSMIT <CEC_TRANSMIT>`,
:ref:`CEC_RECEIVE <CEC_RECEIVE>` and :ref:`CEC_DQEVENT <CEC_DQEVENT>` ioctls
will return the ``EAGAIN`` error code when no message or event is available, and
ioctls :ref:`CEC_TRANSMIT <CEC_TRANSMIT>`,
:ref:`CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` and
:ref:`CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`
all act in non-blocking mode.
all return 0.
Other flags have no effect.
......
......@@ -45,10 +45,24 @@ To query the current CEC logical addresses, applications call
To set new logical addresses, applications fill in
:c:type:`struct cec_log_addrs` and call :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`
with a pointer to this struct. The :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`
is only available if ``CEC_CAP_LOG_ADDRS`` is set (ENOTTY error code is
returned otherwise). This ioctl will block until all requested logical
addresses have been claimed. The :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>` can only be called
by a file handle in initiator mode (see :ref:`CEC_S_MODE`).
is only available if ``CEC_CAP_LOG_ADDRS`` is set (the ``ENOTTY`` error code is
returned otherwise). The :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`
can only be called by a file descriptor in initiator mode (see :ref:`CEC_S_MODE`), if not
the ``EBUSY`` error code will be returned.
To clear existing logical addresses set ``num_log_addrs`` to 0. All other fields
will be ignored in that case. The adapter will go to the unconfigured state.
If the physical address is valid (see :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>`),
then this ioctl will block until all requested logical
addresses have been claimed. If the file descriptor is in non-blocking mode then it will
not wait for the logical addresses to be claimed, instead it just returns 0.
A :ref:`CEC_EVENT_STATE_CHANGE <CEC-EVENT-STATE-CHANGE>` event is sent when the
logical addresses are claimed or cleared.
Attempting to call :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>` when
logical address types are already defined will return with error ``EBUSY``.
.. _cec-log-addrs:
......@@ -63,7 +77,7 @@ by a file handle in initiator mode (see :ref:`CEC_S_MODE`).
- __u8
- ``log_addr`` [CEC_MAX_LOG_ADDRS]
- ``log_addr[CEC_MAX_LOG_ADDRS]``
- The actual logical addresses that were claimed. This is set by the
driver. If no logical address could be claimed, then it is set to
......@@ -136,7 +150,7 @@ by a file handle in initiator mode (see :ref:`CEC_S_MODE`).
- char
- ``osd_name``\ [15]
- ``osd_name[15]``
- The On-Screen Display name as is returned by the
``CEC_MSG_SET_OSD_NAME`` message.
......@@ -145,7 +159,7 @@ by a file handle in initiator mode (see :ref:`CEC_S_MODE`).
- __u8
- ``primary_device_type`` [CEC_MAX_LOG_ADDRS]
- ``primary_device_type[CEC_MAX_LOG_ADDRS]``
- Primary device type for each logical address. See
:ref:`cec-prim-dev-types` for possible types.
......@@ -154,7 +168,7 @@ by a file handle in initiator mode (see :ref:`CEC_S_MODE`).
- __u8
- ``log_addr_type`` [CEC_MAX_LOG_ADDRS]
- ``log_addr_type[CEC_MAX_LOG_ADDRS]``
- Logical address types. See :ref:`cec-log-addr-types` for
possible types. The driver will update this with the actual
......@@ -165,25 +179,27 @@ by a file handle in initiator mode (see :ref:`CEC_S_MODE`).
- __u8
- ``all_device_types`` [CEC_MAX_LOG_ADDRS]
- ``all_device_types[CEC_MAX_LOG_ADDRS]``
- CEC 2.0 specific: all device types. See
:ref:`cec-all-dev-types-flags`. Used to implement the
``CEC_MSG_REPORT_FEATURES`` message. This field is ignored if
``cec_version`` < :ref:`CEC_OP_CEC_VERSION_2_0 <CEC-OP-CEC-VERSION-2-0>`.
- CEC 2.0 specific: the bit mask of all device types. See
:ref:`cec-all-dev-types-flags`. It is used in the CEC 2.0
``CEC_MSG_REPORT_FEATURES`` message. For CEC 1.4 you can either leave
this field to 0, or fill it in according to the CEC 2.0 guidelines to
give the CEC framework more information about the device type, even
though the framework won't use it directly in the CEC message.
- .. row 11
- __u8
- ``features`` [CEC_MAX_LOG_ADDRS][12]
- ``features[CEC_MAX_LOG_ADDRS][12]``
- Features for each logical address. Used to implement the
- Features for each logical address. It is used in the CEC 2.0
``CEC_MSG_REPORT_FEATURES`` message. The 12 bytes include both the
RC Profile and the Device Features. This field is ignored if
``cec_version`` < :ref:`CEC_OP_CEC_VERSION_2_0 <CEC-OP-CEC-VERSION-2-0>`.
RC Profile and the Device Features. For CEC 1.4 you can either leave
this field to all 0, or fill it in according to the CEC 2.0 guidelines to
give the CEC framework more information about the device type, even
though the framework won't use it directly in the CEC message.
.. _cec-versions:
......
......@@ -44,10 +44,21 @@ driver stores the physical address.
To set a new physical address applications store the physical address in
a __u16 and call :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` with a pointer to
this integer. The :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` is only available if
``CEC_CAP_PHYS_ADDR`` is set (ENOTTY error code will be returned
otherwise). The :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` can only be called by a file handle
in initiator mode (see :ref:`CEC_S_MODE`), if not
EBUSY error code will be returned.
``CEC_CAP_PHYS_ADDR`` is set (the ``ENOTTY`` error code will be returned
otherwise). The :ref:`ioctl CEC_ADAP_S_PHYS_ADDR <CEC_ADAP_S_PHYS_ADDR>` can only be called
by a file descriptor in initiator mode (see :ref:`CEC_S_MODE`), if not
the ``EBUSY`` error code will be returned.
To clear an existing physical address use ``CEC_PHYS_ADDR_INVALID``.
The adapter will go to the unconfigured state.
If logical address types have been defined (see :ref:`ioctl CEC_ADAP_S_LOG_ADDRS <CEC_ADAP_S_LOG_ADDRS>`),
then this ioctl will block until all
requested logical addresses have been claimed. If the file descriptor is in non-blocking mode
then it will not wait for the logical addresses to be claimed, instead it just returns 0.
A :ref:`CEC_EVENT_STATE_CHANGE <CEC-EVENT-STATE-CHANGE>` event is sent when the physical address
changes.
The physical address is a 16-bit number where each group of 4 bits
represent a digit of the physical address a.b.c.d where the most
......
......@@ -38,7 +38,7 @@ Description
CEC devices can send asynchronous events. These can be retrieved by
calling :ref:`ioctl CEC_DQEVENT <CEC_DQEVENT>`. If the file descriptor is in
non-blocking mode and no event is pending, then it will return -1 and
set errno to the EAGAIN error code.
set errno to the ``EAGAIN`` error code.
The internal event queues are per-filehandle and per-event type. If
there is no more room in a queue then the last event is overwritten with
......@@ -117,6 +117,8 @@ it is guaranteed that the state did change in between the two events.
- ``ts``
- Timestamp of the event in ns.
The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock. To access
the same clock from userspace use :c:func:`clock_gettime(2)`.
-
......
......@@ -108,7 +108,7 @@ Available initiator modes are:
- This is an exclusive initiator and this file descriptor is the
only one that can transmit CEC messages and make changes to the
CEC adapter. If someone else is already the exclusive initiator
then an attempt to become one will return the EBUSY error code
then an attempt to become one will return the ``EBUSY`` error code
error.
......@@ -140,7 +140,7 @@ Available follower modes are:
- This is a follower and it will receive CEC messages unless there
is an exclusive follower. You cannot become a follower if
:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`
was specified, EINVAL error code is returned in that case.
was specified, the ``EINVAL`` error code is returned in that case.
- .. _`CEC-MODE-EXCL-FOLLOWER`:
......@@ -151,9 +151,9 @@ Available follower modes are:
- This is an exclusive follower and only this file descriptor will
receive CEC messages for processing. If someone else is already
the exclusive follower then an attempt to become one will return
the EBUSY error code error. You cannot become a follower if
the ``EBUSY`` error code. You cannot become a follower if
:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`
was specified, EINVAL error code is returned in that case.
was specified, the ``EINVAL`` error code is returned in that case.
- .. _`CEC-MODE-EXCL-FOLLOWER-PASSTHRU`:
......@@ -166,10 +166,10 @@ Available follower modes are:
CEC device into passthrough mode, allowing the exclusive follower
to handle most core messages instead of relying on the CEC
framework for that. If someone else is already the exclusive
follower then an attempt to become one will return the EBUSY error
code error. You cannot become a follower if :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>`
is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` was specified, EINVAL
error code is returned in that case.
follower then an attempt to become one will return the ``EBUSY`` error
code. You cannot become a follower if :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>`
is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` was specified,
the ``EINVAL`` error code is returned in that case.
- .. _`CEC-MODE-MONITOR`:
......@@ -184,7 +184,7 @@ Available follower modes are:
messages and directed messages for one its logical addresses) will
be reported. This is very useful for debugging. This is only
allowed if the process has the ``CAP_NET_ADMIN`` capability. If
that is not set, then EPERM error code is returned.
that is not set, then the ``EPERM`` error code is returned.
- .. _`CEC-MODE-MONITOR-ALL`:
......@@ -193,15 +193,15 @@ Available follower modes are:
- 0xf0
- Put the file descriptor into 'monitor all' mode. Can only be used
in combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise EINVAL
error code will be returned. In 'monitor all' mode all messages
in combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise
the ``EINVAL`` error code will be returned. In 'monitor all' mode all messages
this CEC device transmits and all messages it receives, including
directed messages for other CEC devices will be reported. This is
very useful for debugging, but not all devices support this. This
mode requires that the :ref:`CEC_CAP_MONITOR_ALL <CEC-CAP-MONITOR-ALL>` capability is set,
otherwise EINVAL error code is returned. This is only allowed if
otherwise the ``EINVAL`` error code is returned. This is only allowed if
the process has the ``CAP_NET_ADMIN`` capability. If that is not
set, then EPERM error code is returned.
set, then the ``EPERM`` error code is returned.
Core message processing details:
......
......@@ -37,19 +37,38 @@ Description
and is currently only available as a staging kernel module.
To receive a CEC message the application has to fill in the
:c:type:`struct cec_msg` and pass it to :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>`.
The :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>` is only available if ``CEC_CAP_RECEIVE`` is set.
``timeout`` field of :c:type:`struct cec_msg` and pass it to :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>`.
If the file descriptor is in non-blocking mode and there are no received
messages pending, then it will return -1 and set errno to the EAGAIN
messages pending, then it will return -1 and set errno to the ``EAGAIN``
error code. If the file descriptor is in blocking mode and ``timeout``
is non-zero and no message arrived within ``timeout`` milliseconds, then
it will return -1 and set errno to the ETIMEDOUT error code.
it will return -1 and set errno to the ``ETIMEDOUT`` error code.
A received message can be:
1. a message received from another CEC device (the ``sequence`` field will
be 0).
2. the result of an earlier non-blocking transmit (the ``sequence`` field will
be non-zero).
To send a CEC message the application has to fill in the
:c:type:`struct cec_msg` and pass it to
:ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>`. The :ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>` is only available if
``CEC_CAP_TRANSMIT`` is set. If there is no more room in the transmit
queue, then it will return -1 and set errno to the EBUSY error code.
queue, then it will return -1 and set errno to the ``EBUSY`` error code.
The transmit queue has enough room for 18 messages (about 1 second worth
of 2-byte messages). Note that the CEC kernel framework will also reply
to core messages (see :ref:cec-core-processing), so it is not a good
idea to fully fill up the transmit queue.
If the file descriptor is in non-blocking mode then the transmit will
return 0 and the result of the transmit will be available via
:ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>` once the transmit has finished
(including waiting for a reply, if requested).
The ``sequence`` field is filled in for every transmit and this can be
checked against the received messages to find the corresponding transmit
result.
.. _cec-msg:
......@@ -67,6 +86,8 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``tx_ts``
- Timestamp in ns of when the last byte of the message was transmitted.
The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock. To access
the same clock from userspace use :c:func:`clock_gettime(2)`.
- .. row 2
......@@ -75,6 +96,8 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``rx_ts``
- Timestamp in ns of when the last byte of the message was received.
The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock. To access
the same clock from userspace use :c:func:`clock_gettime(2)`.
- .. row 3
......@@ -106,10 +129,11 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``sequence``
- The sequence number is automatically assigned by the CEC framework
for all transmitted messages. It can be later used by the
framework to generate an event if a reply for a message was
requested and the message was transmitted in a non-blocking mode.
- A non-zero sequence number is automatically assigned by the CEC framework
for all transmitted messages. It is used by the CEC framework when it queues
the transmit result (when transmit was called in non-blocking mode). This
allows the application to associate the received message with the original
transmit.
- .. row 6
......@@ -133,7 +157,7 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- __u8
- ``msg``\ [16]
- ``msg[16]``
- The message payload. For :ref:`ioctl CEC_TRANSMIT <CEC_TRANSMIT>` this is filled in by the
application. The driver will fill this in for :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>`.
......@@ -148,14 +172,13 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- Wait until this message is replied. If ``reply`` is 0 and the
``timeout`` is 0, then don't wait for a reply but return after
transmitting the message. If there was an error as indicated by the
``tx_status`` field, then ``reply`` and ``timeout`` are
both set to 0 by the driver. Ignored by :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>`. The case
where ``reply`` is 0 (this is the opcode for the Feature Abort
message) and ``timeout`` is non-zero is specifically allowed to
send a message and wait up to ``timeout`` milliseconds for a
transmitting the message. Ignored by :ref:`ioctl CEC_RECEIVE <CEC_RECEIVE>`.
The case where ``reply`` is 0 (this is the opcode for the Feature Abort
message) and ``timeout`` is non-zero is specifically allowed to make it
possible to send a message and wait up to ``timeout`` milliseconds for a
Feature Abort reply. In this case ``rx_status`` will either be set
to :ref:`CEC_RX_STATUS_TIMEOUT <CEC-RX-STATUS-TIMEOUT>` or :ref:`CEC_RX_STATUS_FEATURE_ABORT <CEC-RX-STATUS-FEATURE-ABORT>`.
to :ref:`CEC_RX_STATUS_TIMEOUT <CEC-RX-STATUS-TIMEOUT>` or
:ref:`CEC_RX_STATUS_FEATURE_ABORT <CEC-RX-STATUS-FEATURE-ABORT>`.
- .. row 9
......
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