diff options
Diffstat (limited to 'Documentation/media/uapi/mediactl')
21 files changed, 933 insertions, 13 deletions
diff --git a/Documentation/media/uapi/mediactl/media-controller-intro.rst b/Documentation/media/uapi/mediactl/media-controller-intro.rst index 3e776c0d8276..281c559c2f3c 100644 --- a/Documentation/media/uapi/mediactl/media-controller-intro.rst +++ b/Documentation/media/uapi/mediactl/media-controller-intro.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media-controller-intro: diff --git a/Documentation/media/uapi/mediactl/media-controller-model.rst b/Documentation/media/uapi/mediactl/media-controller-model.rst index 558273cf9570..b6d5902b556d 100644 --- a/Documentation/media/uapi/mediactl/media-controller-model.rst +++ b/Documentation/media/uapi/mediactl/media-controller-model.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media-controller-model: diff --git a/Documentation/media/uapi/mediactl/media-controller.rst b/Documentation/media/uapi/mediactl/media-controller.rst index 0eea4f9a07d5..6e624f690331 100644 --- a/Documentation/media/uapi/mediactl/media-controller.rst +++ b/Documentation/media/uapi/mediactl/media-controller.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. include:: <isonum.txt> @@ -21,6 +28,7 @@ Part IV - Media Controller API media-controller-intro media-controller-model media-types + request-api media-funcs media-header diff --git a/Documentation/media/uapi/mediactl/media-func-close.rst b/Documentation/media/uapi/mediactl/media-func-close.rst index a8f5203afe4b..369ccd4dee56 100644 --- a/Documentation/media/uapi/mediactl/media-func-close.rst +++ b/Documentation/media/uapi/mediactl/media-func-close.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media-func-close: diff --git a/Documentation/media/uapi/mediactl/media-func-ioctl.rst b/Documentation/media/uapi/mediactl/media-func-ioctl.rst index fe072b7c8765..9a990d6480f5 100644 --- a/Documentation/media/uapi/mediactl/media-func-ioctl.rst +++ b/Documentation/media/uapi/mediactl/media-func-ioctl.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media-func-ioctl: diff --git a/Documentation/media/uapi/mediactl/media-func-open.rst b/Documentation/media/uapi/mediactl/media-func-open.rst index 32f53016a9e5..cd2f840ddf73 100644 --- a/Documentation/media/uapi/mediactl/media-func-open.rst +++ b/Documentation/media/uapi/mediactl/media-func-open.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media-func-open: diff --git a/Documentation/media/uapi/mediactl/media-funcs.rst b/Documentation/media/uapi/mediactl/media-funcs.rst index 076856501cdb..87b65df8252a 100644 --- a/Documentation/media/uapi/mediactl/media-funcs.rst +++ b/Documentation/media/uapi/mediactl/media-funcs.rst @@ -1,3 +1,12 @@ +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections + .. _media-user-func: ****************** @@ -16,3 +25,9 @@ Function Reference media-ioc-enum-entities media-ioc-enum-links media-ioc-setup-link + media-ioc-request-alloc + request-func-close + request-func-ioctl + request-func-poll + media-request-ioc-queue + media-request-ioc-reinit diff --git a/Documentation/media/uapi/mediactl/media-header.rst b/Documentation/media/uapi/mediactl/media-header.rst index 96f7b0155e5a..1cb7c88aeff0 100644 --- a/Documentation/media/uapi/mediactl/media-header.rst +++ b/Documentation/media/uapi/mediactl/media-header.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media_header: diff --git a/Documentation/media/uapi/mediactl/media-ioc-device-info.rst b/Documentation/media/uapi/mediactl/media-ioc-device-info.rst index 649cb3d9e058..f8038cfb708c 100644 --- a/Documentation/media/uapi/mediactl/media-ioc-device-info.rst +++ b/Documentation/media/uapi/mediactl/media-ioc-device-info.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media_ioc_device_info: @@ -26,6 +33,7 @@ Arguments File descriptor returned by :ref:`open() <media-func-open>`. ``argp`` + Pointer to struct :c:type:`media_device_info`. Description diff --git a/Documentation/media/uapi/mediactl/media-ioc-enum-entities.rst b/Documentation/media/uapi/mediactl/media-ioc-enum-entities.rst index fc2e39c070c9..6218d9cbdd83 100644 --- a/Documentation/media/uapi/mediactl/media-ioc-enum-entities.rst +++ b/Documentation/media/uapi/mediactl/media-ioc-enum-entities.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media_ioc_enum_entities: @@ -26,6 +33,7 @@ Arguments File descriptor returned by :ref:`open() <media-func-open>`. ``argp`` + Pointer to struct :c:type:`media_entity_desc`. Description diff --git a/Documentation/media/uapi/mediactl/media-ioc-enum-links.rst b/Documentation/media/uapi/mediactl/media-ioc-enum-links.rst index f158c134e9b0..a982f16e55a4 100644 --- a/Documentation/media/uapi/mediactl/media-ioc-enum-links.rst +++ b/Documentation/media/uapi/mediactl/media-ioc-enum-links.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media_ioc_enum_links: @@ -26,6 +33,7 @@ Arguments File descriptor returned by :ref:`open() <media-func-open>`. ``argp`` + Pointer to struct :c:type:`media_links_enum`. Description diff --git a/Documentation/media/uapi/mediactl/media-ioc-g-topology.rst b/Documentation/media/uapi/mediactl/media-ioc-g-topology.rst index bac128c7eda9..0a7d76ac8ded 100644 --- a/Documentation/media/uapi/mediactl/media-ioc-g-topology.rst +++ b/Documentation/media/uapi/mediactl/media-ioc-g-topology.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media_ioc_g_topology: @@ -26,6 +33,7 @@ Arguments File descriptor returned by :ref:`open() <media-func-open>`. ``argp`` + Pointer to struct :c:type:`media_v2_topology`. Description diff --git a/Documentation/media/uapi/mediactl/media-ioc-request-alloc.rst b/Documentation/media/uapi/mediactl/media-ioc-request-alloc.rst new file mode 100644 index 000000000000..6d4ca4ada2e0 --- /dev/null +++ b/Documentation/media/uapi/mediactl/media-ioc-request-alloc.rst @@ -0,0 +1,90 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _media_ioc_request_alloc: + +***************************** +ioctl MEDIA_IOC_REQUEST_ALLOC +***************************** + +Name +==== + +MEDIA_IOC_REQUEST_ALLOC - Allocate a request + + +Synopsis +======== + +.. c:function:: int ioctl( int fd, MEDIA_IOC_REQUEST_ALLOC, int *argp ) + :name: MEDIA_IOC_REQUEST_ALLOC + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <media-func-open>`. + +``argp`` + Pointer to an integer. + + +Description +=========== + +If the media device supports :ref:`requests <media-request-api>`, then +this ioctl can be used to allocate a request. If it is not supported, then +``errno`` is set to ``ENOTTY``. A request is accessed through a file descriptor +that is returned in ``*argp``. + +If the request was successfully allocated, then the request file descriptor +can be passed to the :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`, +:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, +:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and +:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctls. + +In addition, the request can be queued by calling +:ref:`MEDIA_REQUEST_IOC_QUEUE` and re-initialized by calling +:ref:`MEDIA_REQUEST_IOC_REINIT`. + +Finally, the file descriptor can be :ref:`polled <request-func-poll>` to wait +for the request to complete. + +The request will remain allocated until all the file descriptors associated +with it are closed by :ref:`close() <request-func-close>` and the driver no +longer uses the request internally. See also +:ref:`here <media-request-life-time>` for more information. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +ENOTTY + The driver has no support for requests. diff --git a/Documentation/media/uapi/mediactl/media-ioc-setup-link.rst b/Documentation/media/uapi/mediactl/media-ioc-setup-link.rst index ae5194940100..ae39dbbe48a0 100644 --- a/Documentation/media/uapi/mediactl/media-ioc-setup-link.rst +++ b/Documentation/media/uapi/mediactl/media-ioc-setup-link.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media_ioc_setup_link: @@ -26,6 +33,7 @@ Arguments File descriptor returned by :ref:`open() <media-func-open>`. ``argp`` + Pointer to struct :c:type:`media_link_desc`. Description diff --git a/Documentation/media/uapi/mediactl/media-request-ioc-queue.rst b/Documentation/media/uapi/mediactl/media-request-ioc-queue.rst new file mode 100644 index 000000000000..fc8458746d51 --- /dev/null +++ b/Documentation/media/uapi/mediactl/media-request-ioc-queue.rst @@ -0,0 +1,102 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _media_request_ioc_queue: + +***************************** +ioctl MEDIA_REQUEST_IOC_QUEUE +***************************** + +Name +==== + +MEDIA_REQUEST_IOC_QUEUE - Queue a request + + +Synopsis +======== + +.. c:function:: int ioctl( int request_fd, MEDIA_REQUEST_IOC_QUEUE ) + :name: MEDIA_REQUEST_IOC_QUEUE + + +Arguments +========= + +``request_fd`` + File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. + + +Description +=========== + +If the media device supports :ref:`requests <media-request-api>`, then +this request ioctl can be used to queue a previously allocated request. + +If the request was successfully queued, then the file descriptor can be +:ref:`polled <request-func-poll>` to wait for the request to complete. + +If the request was already queued before, then ``EBUSY`` is returned. +Other errors can be returned if the contents of the request contained +invalid or inconsistent data, see the next section for a list of +common error codes. On error both the request and driver state are unchanged. + +Once a request is queued, then the driver is required to gracefully handle +errors that occur when the request is applied to the hardware. The +exception is the ``EIO`` error which signals a fatal error that requires +the application to stop streaming to reset the hardware state. + +It is not allowed to mix queuing requests with queuing buffers directly +(without a request). ``EBUSY`` will be returned if the first buffer was +queued directly and you next try to queue a request, or vice versa. + +A request must contain at least one buffer, otherwise this ioctl will +return an ``ENOENT`` error. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +EBUSY + The request was already queued or the application queued the first + buffer directly, but later attempted to use a request. It is not permitted + to mix the two APIs. +ENOENT + The request did not contain any buffers. All requests are required + to have at least one buffer. This can also be returned if some required + configuration is missing in the request. +ENOMEM + Out of memory when allocating internal data structures for this + request. +EINVAL + The request has invalid data. +EIO + The hardware is in a bad state. To recover, the application needs to + stop streaming to reset the hardware state and then try to restart + streaming. diff --git a/Documentation/media/uapi/mediactl/media-request-ioc-reinit.rst b/Documentation/media/uapi/mediactl/media-request-ioc-reinit.rst new file mode 100644 index 000000000000..61381e87665a --- /dev/null +++ b/Documentation/media/uapi/mediactl/media-request-ioc-reinit.rst @@ -0,0 +1,75 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _media_request_ioc_reinit: + +****************************** +ioctl MEDIA_REQUEST_IOC_REINIT +****************************** + +Name +==== + +MEDIA_REQUEST_IOC_REINIT - Re-initialize a request + + +Synopsis +======== + +.. c:function:: int ioctl( int request_fd, MEDIA_REQUEST_IOC_REINIT ) + :name: MEDIA_REQUEST_IOC_REINIT + + +Arguments +========= + +``request_fd`` + File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. + +Description +=========== + +If the media device supports :ref:`requests <media-request-api>`, then +this request ioctl can be used to re-initialize a previously allocated +request. + +Re-initializing a request will clear any existing data from the request. +This avoids having to :ref:`close() <request-func-close>` a completed +request and allocate a new request. Instead the completed request can just +be re-initialized and it is ready to be used again. + +A request can only be re-initialized if it either has not been queued +yet, or if it was queued and completed. Otherwise it will set ``errno`` +to ``EBUSY``. No other error codes can be returned. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. + +EBUSY + The request is queued but not yet completed. diff --git a/Documentation/media/uapi/mediactl/media-types.rst b/Documentation/media/uapi/mediactl/media-types.rst index e4c57c8f4553..8627587b7075 100644 --- a/Documentation/media/uapi/mediactl/media-types.rst +++ b/Documentation/media/uapi/mediactl/media-types.rst @@ -1,4 +1,11 @@ -.. -*- coding: utf-8; mode: rst -*- +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media-controller-types: diff --git a/Documentation/media/uapi/mediactl/request-api.rst b/Documentation/media/uapi/mediactl/request-api.rst new file mode 100644 index 000000000000..4b25ad03f45a --- /dev/null +++ b/Documentation/media/uapi/mediactl/request-api.rst @@ -0,0 +1,276 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _media-request-api: + +Request API +=========== + +The Request API has been designed to allow V4L2 to deal with requirements of +modern devices (stateless codecs, complex camera pipelines, ...) and APIs +(Android Codec v2). One such requirement is the ability for devices belonging to +the same pipeline to reconfigure and collaborate closely on a per-frame basis. +Another is support of stateless codecs, which require controls to be applied +to specific frames (aka 'per-frame controls') in order to be used efficiently. + +While the initial use-case was V4L2, it can be extended to other subsystems +as well, as long as they use the media controller. + +Supporting these features without the Request API is not always possible and if +it is, it is terribly inefficient: user-space would have to flush all activity +on the media pipeline, reconfigure it for the next frame, queue the buffers to +be processed with that configuration, and wait until they are all available for +dequeuing before considering the next frame. This defeats the purpose of having +buffer queues since in practice only one buffer would be queued at a time. + +The Request API allows a specific configuration of the pipeline (media +controller topology + configuration for each media entity) to be associated with +specific buffers. This allows user-space to schedule several tasks ("requests") +with different configurations in advance, knowing that the configuration will be +applied when needed to get the expected result. Configuration values at the time +of request completion are also available for reading. + +Usage +===== + +The Request API extends the Media Controller API and cooperates with +subsystem-specific APIs to support request usage. At the Media Controller +level, requests are allocated from the supporting Media Controller device +node. Their life cycle is then managed through the request file descriptors in +an opaque way. Configuration data, buffer handles and processing results +stored in requests are accessed through subsystem-specific APIs extended for +request support, such as V4L2 APIs that take an explicit ``request_fd`` +parameter. + +Request Allocation +------------------ + +User-space allocates requests using :ref:`MEDIA_IOC_REQUEST_ALLOC` +for the media device node. This returns a file descriptor representing the +request. Typically, several such requests will be allocated. + +Request Preparation +------------------- + +Standard V4L2 ioctls can then receive a request file descriptor to express the +fact that the ioctl is part of said request, and is not to be applied +immediately. See :ref:`MEDIA_IOC_REQUEST_ALLOC` for a list of ioctls that +support this. Configurations set with a ``request_fd`` parameter are stored +instead of being immediately applied, and buffers queued to a request do not +enter the regular buffer queue until the request itself is queued. + +Request Submission +------------------ + +Once the configuration and buffers of the request are specified, it can be +queued by calling :ref:`MEDIA_REQUEST_IOC_QUEUE` on the request file descriptor. +A request must contain at least one buffer, otherwise ``ENOENT`` is returned. +A queued request cannot be modified anymore. + +.. caution:: + For :ref:`memory-to-memory devices <codec>` you can use requests only for + output buffers, not for capture buffers. Attempting to add a capture buffer + to a request will result in an ``EACCES`` error. + +If the request contains configurations for multiple entities, individual drivers +may synchronize so the requested pipeline's topology is applied before the +buffers are processed. Media controller drivers do a best effort implementation +since perfect atomicity may not be possible due to hardware limitations. + +.. caution:: + + It is not allowed to mix queuing requests with directly queuing buffers: + whichever method is used first locks this in place until + :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` is called or the device is + :ref:`closed <func-close>`. Attempts to directly queue a buffer when earlier + a buffer was queued via a request or vice versa will result in an ``EBUSY`` + error. + +Controls can still be set without a request and are applied immediately, +regardless of whether a request is in use or not. + +.. caution:: + + Setting the same control through a request and also directly can lead to + undefined behavior! + +User-space can :ref:`poll() <request-func-poll>` a request file descriptor in +order to wait until the request completes. A request is considered complete +once all its associated buffers are available for dequeuing and all the +associated controls have been updated with the values at the time of completion. +Note that user-space does not need to wait for the request to complete to +dequeue its buffers: buffers that are available halfway through a request can +be dequeued independently of the request's state. + +A completed request contains the state of the device after the request was +executed. User-space can query that state by calling +:ref:`ioctl VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` with the request file +descriptor. Calling :ref:`ioctl VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` for a +request that has been queued but not yet completed will return ``EBUSY`` +since the control values might be changed at any time by the driver while the +request is in flight. + +.. _media-request-life-time: + +Recycling and Destruction +------------------------- + +Finally, a completed request can either be discarded or be reused. Calling +:ref:`close() <request-func-close>` on a request file descriptor will make +that file descriptor unusable and the request will be freed once it is no +longer in use by the kernel. That is, if the request is queued and then the +file descriptor is closed, then it won't be freed until the driver completed +the request. + +The :ref:`MEDIA_REQUEST_IOC_REINIT` will clear a request's state and make it +available again. No state is retained by this operation: the request is as +if it had just been allocated. + +Example for a Codec Device +-------------------------- + +For use-cases such as :ref:`codecs <codec>`, the request API can be used +to associate specific controls to +be applied by the driver for the OUTPUT buffer, allowing user-space +to queue many such buffers in advance. It can also take advantage of requests' +ability to capture the state of controls when the request completes to read back +information that may be subject to change. + +Put into code, after obtaining a request, user-space can assign controls and one +OUTPUT buffer to it: + +.. code-block:: c + + struct v4l2_buffer buf; + struct v4l2_ext_controls ctrls; + int req_fd; + ... + if (ioctl(media_fd, MEDIA_IOC_REQUEST_ALLOC, &req_fd)) + return errno; + ... + ctrls.which = V4L2_CTRL_WHICH_REQUEST_VAL; + ctrls.request_fd = req_fd; + if (ioctl(codec_fd, VIDIOC_S_EXT_CTRLS, &ctrls)) + return errno; + ... + buf.type = V4L2_BUF_TYPE_VIDEO_OUTPUT; + buf.flags |= V4L2_BUF_FLAG_REQUEST_FD; + buf.request_fd = req_fd; + if (ioctl(codec_fd, VIDIOC_QBUF, &buf)) + return errno; + +Note that it is not allowed to use the Request API for CAPTURE buffers +since there are no per-frame settings to report there. + +Once the request is fully prepared, it can be queued to the driver: + +.. code-block:: c + + if (ioctl(req_fd, MEDIA_REQUEST_IOC_QUEUE)) + return errno; + +User-space can then either wait for the request to complete by calling poll() on +its file descriptor, or start dequeuing CAPTURE buffers. Most likely, it will +want to get CAPTURE buffers as soon as possible and this can be done using a +regular :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>`: + +.. code-block:: c + + struct v4l2_buffer buf; + + memset(&buf, 0, sizeof(buf)); + buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + if (ioctl(codec_fd, VIDIOC_DQBUF, &buf)) + return errno; + +Note that this example assumes for simplicity that for every OUTPUT buffer +there will be one CAPTURE buffer, but this does not have to be the case. + +We can then, after ensuring that the request is completed via polling the +request file descriptor, query control values at the time of its completion via +a call to :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`. +This is particularly useful for volatile controls for which we want to +query values as soon as the capture buffer is produced. + +.. code-block:: c + + struct pollfd pfd = { .events = POLLPRI, .fd = req_fd }; + poll(&pfd, 1, -1); + ... + ctrls.which = V4L2_CTRL_WHICH_REQUEST_VAL; + ctrls.request_fd = req_fd; + if (ioctl(codec_fd, VIDIOC_G_EXT_CTRLS, &ctrls)) + return errno; + +Once we don't need the request anymore, we can either recycle it for reuse with +:ref:`MEDIA_REQUEST_IOC_REINIT`... + +.. code-block:: c + + if (ioctl(req_fd, MEDIA_REQUEST_IOC_REINIT)) + return errno; + +... or close its file descriptor to completely dispose of it. + +.. code-block:: c + + close(req_fd); + +Example for a Simple Capture Device +----------------------------------- + +With a simple capture device, requests can be used to specify controls to apply +for a given CAPTURE buffer. + +.. code-block:: c + + struct v4l2_buffer buf; + struct v4l2_ext_controls ctrls; + int req_fd; + ... + if (ioctl(media_fd, MEDIA_IOC_REQUEST_ALLOC, &req_fd)) + return errno; + ... + ctrls.which = V4L2_CTRL_WHICH_REQUEST_VAL; + ctrls.request_fd = req_fd; + if (ioctl(camera_fd, VIDIOC_S_EXT_CTRLS, &ctrls)) + return errno; + ... + buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + buf.flags |= V4L2_BUF_FLAG_REQUEST_FD; + buf.request_fd = req_fd; + if (ioctl(camera_fd, VIDIOC_QBUF, &buf)) + return errno; + +Once the request is fully prepared, it can be queued to the driver: + +.. code-block:: c + + if (ioctl(req_fd, MEDIA_REQUEST_IOC_QUEUE)) + return errno; + +User-space can then dequeue buffers, wait for the request completion, query +controls and recycle the request as in the M2M example above. diff --git a/Documentation/media/uapi/mediactl/request-func-close.rst b/Documentation/media/uapi/mediactl/request-func-close.rst new file mode 100644 index 000000000000..2cff7770558e --- /dev/null +++ b/Documentation/media/uapi/mediactl/request-func-close.rst @@ -0,0 +1,73 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _request-func-close: + +*************** +request close() +*************** + +Name +==== + +request-close - Close a request file descriptor + + +Synopsis +======== + +.. code-block:: c + + #include <unistd.h> + + +.. c:function:: int close( int fd ) + :name: req-close + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. + + +Description +=========== + +Closes the request file descriptor. Resources associated with the request +are freed once all file descriptors associated with the request are closed +and the driver has completed the request. +See :ref:`here <media-request-life-time>` for more information. + + +Return Value +============ + +:ref:`close() <request-func-close>` returns 0 on success. On error, -1 is +returned, and ``errno`` is set appropriately. Possible error codes are: + +EBADF + ``fd`` is not a valid open file descriptor. diff --git a/Documentation/media/uapi/mediactl/request-func-ioctl.rst b/Documentation/media/uapi/mediactl/request-func-ioctl.rst new file mode 100644 index 000000000000..de0781c61873 --- /dev/null +++ b/Documentation/media/uapi/mediactl/request-func-ioctl.rst @@ -0,0 +1,91 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _request-func-ioctl: + +*************** +request ioctl() +*************** + +Name +==== + +request-ioctl - Control a request file descriptor + + +Synopsis +======== + +.. code-block:: c + + #include <sys/ioctl.h> + + +.. c:function:: int ioctl( int fd, int cmd, void *argp ) + :name: req-ioctl + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. + +``cmd`` + The request ioctl command code as defined in the media.h header file, for + example :ref:`MEDIA_REQUEST_IOC_QUEUE`. + +``argp`` + Pointer to a request-specific structure. + + +Description +=========== + +The :ref:`ioctl() <request-func-ioctl>` function manipulates request +parameters. The argument ``fd`` must be an open file descriptor. + +The ioctl ``cmd`` code specifies the request function to be called. It +has encoded in it whether the argument is an input, output or read/write +parameter, and the size of the argument ``argp`` in bytes. + +Macros and structures definitions specifying request ioctl commands and +their parameters are located in the media.h header file. All request ioctl +commands, their respective function and parameters are specified in +:ref:`media-user-func`. + + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +Command-specific error codes are listed in the individual command +descriptions. + +When an ioctl that takes an output or read/write parameter fails, the +parameter remains unmodified. diff --git a/Documentation/media/uapi/mediactl/request-func-poll.rst b/Documentation/media/uapi/mediactl/request-func-poll.rst new file mode 100644 index 000000000000..ebaf33e21873 --- /dev/null +++ b/Documentation/media/uapi/mediactl/request-func-poll.rst @@ -0,0 +1,101 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/media/uapi/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _request-func-poll: + +************** +request poll() +************** + +Name +==== + +request-poll - Wait for some event on a file descriptor + + +Synopsis +======== + +.. code-block:: c + + #include <sys/poll.h> + + +.. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout ) + :name: request-poll + +Arguments +========= + +``ufds`` + List of file descriptor events to be watched + +``nfds`` + Number of file descriptor events at the \*ufds array + +``timeout`` + Timeout to wait for events + + +Description +=========== + +With the :c:func:`poll() <request-func-poll>` function applications can wait +for a request to complete. + +On success :c:func:`poll() <request-func-poll>` returns the number of file +descriptors that have been selected (that is, file descriptors for which the +``revents`` field of the respective struct :c:type:`pollfd` +is non-zero). Request file descriptor set the ``POLLPRI`` flag in ``revents`` +when the request was completed. When the function times out it returns +a value of zero, on failure it returns -1 and the ``errno`` variable is +set appropriately. + +Attempting to poll for a request that is not yet queued will +set the ``POLLERR`` flag in ``revents``. + + +Return Value +============ + +On success, :c:func:`poll() <request-func-poll>` returns the number of +structures which have non-zero ``revents`` fields, or zero if the call +timed out. On error -1 is returned, and the ``errno`` variable is set +appropriately: + +``EBADF`` + One or more of the ``ufds`` members specify an invalid file + descriptor. + +``EFAULT`` + ``ufds`` references an inaccessible memory area. + +``EINTR`` + The call was interrupted by a signal. + +``EINVAL`` + The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use + ``getrlimit()`` to obtain this value. |