History log of /openbmc/linux/include/media/media-entity.h (Results 1 – 25 of 215)
Revision (<<< Hide revision tags) (Show revision tags >>>) Date Author Comments
Revision tags: v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14, v6.6.13, v6.6.12
# ebb6fb7f 14-Jan-2024 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: Add num_links flag to media_pad

[ Upstream commit baeddf94aa61879b118f2faa37ed126d772670cc ]

Maintain a counter of the links connected to a pad in the media_pad
structure. This helps che

media: mc: Add num_links flag to media_pad

[ Upstream commit baeddf94aa61879b118f2faa37ed126d772670cc ]

Maintain a counter of the links connected to a pad in the media_pad
structure. This helps checking if a pad is connected to anything, which
will be used in the pipeline building code.

Cc: stable@vger.kernel.org # 6.1
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Revision tags: v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14, v6.6.13, v6.6.12
# ebb6fb7f 14-Jan-2024 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: Add num_links flag to media_pad

[ Upstream commit baeddf94aa61879b118f2faa37ed126d772670cc ]

Maintain a counter of the links connected to a pad in the media_pad
structure. This helps che

media: mc: Add num_links flag to media_pad

[ Upstream commit baeddf94aa61879b118f2faa37ed126d772670cc ]

Maintain a counter of the links connected to a pad in the media_pad
structure. This helps checking if a pad is connected to anything, which
will be used in the pipeline building code.

Cc: stable@vger.kernel.org # 6.1
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...


Revision tags: v6.6.11, v6.6.10, v6.6.9, v6.6.8, v6.6.7, v6.6.6, v6.6.5, v6.6.4, v6.6.3, v6.6.2, v6.5.11, v6.6.1, v6.5.10, v6.6, v6.5.9, v6.5.8, v6.5.7, v6.5.6, v6.5.5, v6.5.4, v6.5.3, v6.5.2, v6.1.51, v6.5.1, v6.1.50, v6.5, v6.1.49, v6.1.48, v6.1.46, v6.1.45, v6.1.44, v6.1.43, v6.1.42, v6.1.41, v6.1.40, v6.1.39, v6.1.38, v6.1.37, v6.1.36, v6.4, v6.1.35, v6.1.34, v6.1.33, v6.1.32, v6.1.31, v6.1.30, v6.1.29, v6.1.28, v6.1.27, v6.1.26
# 4fd463e9 25-Apr-2023 Sakari Ailus <sakari.ailus@linux.intel.com>

media: mc: Make media_get_pad_index() use pad type flag

Use the pad flag specifying the pad type instead of a boolean in
preparation for internal source pads.

Also make the loop variable unsigned.

media: mc: Make media_get_pad_index() use pad type flag

Use the pad flag specifying the pad type instead of a boolean in
preparation for internal source pads.

Also make the loop variable unsigned.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

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# ec178312 05-May-2023 Sakari Ailus <sakari.ailus@linux.intel.com>

media: mc: Make media_entity_get_fwnode_pad() fwnode argument const

fwnode_graph_parse_endpoint() fwnode argument is now const, therefore make
media_entity_get_fwnode_pad() fwnode argument const as

media: mc: Make media_entity_get_fwnode_pad() fwnode argument const

fwnode_graph_parse_endpoint() fwnode argument is now const, therefore make
media_entity_get_fwnode_pad() fwnode argument const as well.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

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Revision tags: v6.3, v6.1.25, v6.1.24, v6.1.23, v6.1.22, v6.1.21, v6.1.20, v6.1.19, v6.1.18, v6.1.17, v6.1.16, v6.1.15, v6.1.14, v6.1.13, v6.2, v6.1.12, v6.1.11, v6.1.10, v6.1.9, v6.1.8, v6.1.7, v6.1.6, v6.1.5, v6.0.19, v6.0.18, v6.1.4, v6.1.3, v6.0.17, v6.1.2, v6.0.16, v6.1.1, v6.0.15
# eac564de 21-Dec-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: entity: Add entity iterator for media_pipeline

Add a media_pipeline_for_each_entity() macro to iterate over entities in
a pipeline. This should be used by driver as a replacement of the
m

media: mc: entity: Add entity iterator for media_pipeline

Add a media_pipeline_for_each_entity() macro to iterate over entities in
a pipeline. This should be used by driver as a replacement of the
media_graph_walk API, as iterating over the media_pipeline uses the
cached list of pads and is thus more efficient.

Deprecate the media_graph_walk API to indicate it shouldn't be used in
new drivers.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# d10ac51e 21-Dec-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: entity: Add pad iterator for media_pipeline

Add a media_pipeline_for_each_pad() macro to iterate over pads in a
pipeline. This should be used by driver as a replacement of the
media_graph

media: mc: entity: Add pad iterator for media_pipeline

Add a media_pipeline_for_each_pad() macro to iterate over pads in a
pipeline. This should be used by driver as a replacement of the
media_graph_walk API, as iterating over the media_pipeline uses the
cached list of pads and is thus more efficient.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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Revision tags: v6.0.14, v6.0.13, v6.1, v6.0.12, v6.0.11, v6.0.10, v5.15.80, v6.0.9, v5.15.79, v6.0.8, v5.15.78, v6.0.7, v5.15.77, v5.15.76, v6.0.6, v6.0.5, v5.15.75, v6.0.4, v6.0.3, v6.0.2, v5.15.74, v5.15.73, v6.0.1, v5.15.72, v6.0, v5.15.71, v5.15.70, v5.15.69, v5.15.68, v5.15.67, v5.15.66, v5.15.65, v5.15.64, v5.15.63, v5.15.62, v5.15.61, v5.15.60, v5.15.59, v5.19, v5.15.58, v5.15.57, v5.15.56, v5.15.55, v5.15.54, v5.15.53, v5.15.52, v5.15.51, v5.15.50, v5.15.49, v5.15.48, v5.15.47, v5.15.46, v5.15.45, v5.15.44, v5.15.43, v5.15.42, v5.18, v5.15.41, v5.15.40, v5.15.39, v5.15.38, v5.15.37, v5.15.36, v5.15.35, v5.15.34, v5.15.33, v5.15.32, v5.15.31, v5.17, v5.15.30, v5.15.29, v5.15.28, v5.15.27, v5.15.26, v5.15.25, v5.15.24, v5.15.23, v5.15.22, v5.15.21, v5.15.20, v5.15.19, v5.15.18, v5.15.17, v5.4.173, v5.15.16, v5.15.15
# 1ec06124 13-Jan-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: Improve the media_entity_has_pad_interdep() documentation

Document the function parameters, the requirements on the pad0 and pad1
arguments, the locking requirements and the return value.

media: mc: Improve the media_entity_has_pad_interdep() documentation

Document the function parameters, the requirements on the pad0 and pad1
arguments, the locking requirements and the return value. Also improve
the documentation of the corresponding .has_pad_interdep() operation,
stating clearly that the operation must be called through the
media_entity_has_pad_interdep() function only.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# a8278ad7 08-Sep-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: Fix documentation typos in media-entity.h

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>


# 9e3576a1 31-Aug-2022 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

media: mc: convert pipeline funcs to take media_pad

Now that the pipeline is stored into pads instead of entities, we can
change the relevant functions to take pads instead of entities.

Signed-off-

media: mc: convert pipeline funcs to take media_pad

Now that the pipeline is stored into pads instead of entities, we can
change the relevant functions to take pads instead of entities.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 5b4f9a72 31-Aug-2022 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

media: mc: entity: Add has_pad_interdep entity operation

Add a new media entity operation, has_pad_interdep. The optional op is
used to discover the pad interdependencies inside an entity during the

media: mc: entity: Add has_pad_interdep entity operation

Add a new media entity operation, has_pad_interdep. The optional op is
used to discover the pad interdependencies inside an entity during the
pipeline construction.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# ae219872 31-Aug-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: entity: Rewrite media_pipeline_start()

[Note: the code is mostly from Laurent but the patch description is from Tomi]

The media_pipeline_start() and media_pipeline_stop() functions use t

media: mc: entity: Rewrite media_pipeline_start()

[Note: the code is mostly from Laurent but the patch description is from Tomi]

The media_pipeline_start() and media_pipeline_stop() functions use the
media graph walk API to traverse the graph and validate the pipeline.
The graph walk traverses the media graph following links between the
entities.

Also, while the pipeline can't change between the start and stop calls,
the graph is walked again from scratch at stop time, or any time a
driver needs to inspect the pipeline.

With the upcoming multiplexed streams support we will need a bit more
intelligent pipeline construction, as e.g. two independent streams may
be passing through a single entity via separate pads in which case
those pads should not be part of the same pipeline.

This patch essentially rewrites the media_pipeline_start/stop so that
a pipeline is defined as a set of pads instead of entities and the media
graph traversal considers the pad interdependencies when choosing which
links to follow.

Currently all the entity's pads are considered as interdependent. This
means that the behavior with all the current drivers stays the same, but
in the future we can define a more fine-grained pipeline construction.

Additionally the media pipeline's pads are cached at
media_pipeline_start() time, and re-used at media_pipeline_stop() which
avoid the need to re-walk the whole graph as the previous implementation
did.

Also, caching pads in the pipeline can serve in the future as the
foundation to provide a better API than the media graph walk to drivers
to iterate over pads and entities in the pipeline.

Note that the old media_pipeline_start/stop used the media graph walk
API. The new version does not use the media graph walk API, but instead
a new implementation.

There are two reasons for not changing the graph walk: it proved to be
rather difficult to change the graph walk to have the features
implemented in this patch, and second, this keeps the backward
compatibility of the graph walk as there are users of the graph walk API

The long term plan is that all the existing code would be converted to
use the new cached pipeline, thus allowing us to remove the graph walk.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# d9f44345 31-Aug-2022 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

media: mc: entity: add alloc variant of pipeline_start

Add new variant of media_pipeline_start(), media_pipeline_alloc_start().

media_pipeline_alloc_start() can be used by drivers that do not need

media: mc: entity: add alloc variant of pipeline_start

Add new variant of media_pipeline_start(), media_pipeline_alloc_start().

media_pipeline_alloc_start() can be used by drivers that do not need to
extend the media_pipeline. The function will either use the pipeline
already associated with the entity, if such exists, or allocate a new
pipeline.

When media_pipeline_stop() is called and the pipeline's use count drops
to zero, the pipeline is automatically freed.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 72b60335 31-Aug-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: entity: Add media_entity_pipeline() to access the media pipeline

Replace direct access to the pipe field in drivers with a new helper
function. This will allow easier refactoring of media

media: mc: entity: Add media_entity_pipeline() to access the media pipeline

Replace direct access to the pipe field in drivers with a new helper
function. This will allow easier refactoring of media pipeline handling
in the MC core behind the scenes without affecting drivers.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 49b38947 31-Aug-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc: entity: Merge media_entity_enum_init and __media_entity_enum_init

The media_entity_enum_init() function is a wrapper around
__media_entity_enum_init() that turns a media_device pointer ar

media: mc: entity: Merge media_entity_enum_init and __media_entity_enum_init

The media_entity_enum_init() function is a wrapper around
__media_entity_enum_init() that turns a media_device pointer argument
into the maximum entity ID in the corresponding media graph.
__media_entity_enum_init() is never used outside of
media_entity_enum_init(), so the two functions can be merged together.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 8db465f7 31-Aug-2022 Jacopo Mondi <jacopo+renesas@jmondi.org>

media: mc: entity: Add iterator helper for entity pads

Add an iterator helper to easily cycle through all pads in an entity and
use it in media-entity and media-device code where appropriate.

Signe

media: mc: entity: Add iterator helper for entity pads

Add an iterator helper to easily cycle through all pads in an entity and
use it in media-entity and media-device code where appropriate.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# b7319e2b 31-Aug-2022 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

media: mc: entity: Rename streaming_count -> start_count

'streaming_count' is a bit misleading name, as the count is increased
with media_pipeline_start(). Let's rename it to 'start_count' instead.

media: mc: entity: Rename streaming_count -> start_count

'streaming_count' is a bit misleading name, as the count is increased
with media_pipeline_start(). Let's rename it to 'start_count' instead.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# c7097c80 31-Aug-2022 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

media: media-entity.h: add include for min()

./include/media/media-entity.h:595:34: error: implicit declaration of function ‘min’

Include minmax.h to get the definition for min().

Signed-off-by: T

media: media-entity.h: add include for min()

./include/media/media-entity.h:595:34: error: implicit declaration of function ‘min’

Include minmax.h to get the definition for min().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 03b28286 14-Jun-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc-entity: Add a new helper function to get a remote pad for a pad

The newly added media_entity_remote_source_pad_unique() helper function
handles use cases where the entity has a link enable

media: mc-entity: Add a new helper function to get a remote pad for a pad

The newly added media_entity_remote_source_pad_unique() helper function
handles use cases where the entity has a link enabled uniqueness
constraint covering all pads. There are use cases where the constraint
covers a specific pad only. Add a new media_pad_remote_pad_unique()
function to handle this. It operates as
media_entity_remote_source_pad_unique(), but on a given pad instead of
on the entity.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 5680fe45 14-Jun-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc-entity: Add a new helper function to get a remote pad

The media_entity_remote_pad_first() helper function returns the first
remote pad it finds connected to a given pad. Beside being possi

media: mc-entity: Add a new helper function to get a remote pad

The media_entity_remote_pad_first() helper function returns the first
remote pad it finds connected to a given pad. Beside being possibly
non-deterministic (as it stops at the first enabled link), the fact that
it returns the first match makes it unsuitable for drivers that need to
guarantee that a single link is enabled, for instance when an entity can
process data from one of multiple sources at a time.

For those use cases, add a new helper function,
media_entity_remote_pad_unique(), that operates on an entity and returns
a remote pad, with a guarantee that only one link is enabled. To ease
its use in drivers, also add an inline wrapper that locates source pads
specifically. A wrapper that locates sink pads can easily be added when
needed.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# b2e44430 25-Jun-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: mc-entity: Rename media_entity_remote_pad() to media_pad_remote_pad_first()

The media_entity_remote_pad() is misnamed, as it operates on a pad and
not an entity. Rename it to media_pad_remote

media: mc-entity: Rename media_entity_remote_pad() to media_pad_remote_pad_first()

The media_entity_remote_pad() is misnamed, as it operates on a pad and
not an entity. Rename it to media_pad_remote_pad_first() to clarify its
behaviour.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 1ed3d644 07-Jul-2022 Daniel Scally <djrscally@gmail.com>

media: entity: Add iterator for entity data links

Iterating over the links for an entity is a somewhat common need
through the media subsystem, but generally the assumption is that
they will all be

media: entity: Add iterator for entity data links

Iterating over the links for an entity is a somewhat common need
through the media subsystem, but generally the assumption is that
they will all be data links. To meet that assumption add a new macro
that iterates through an entity's links and skips non-data links.

Signed-off-by: Daniel Scally <djrscally@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 3c9b04d9 08-Apr-2022 Ian Jamison <ian.dev@arkver.com>

media: media-entity.h: Fix documentation for media_create_intf_link

The documentation comment was inserted between the return type
and the function name. Reunite the lines.

Signed-off-by: Ian Jamis

media: media-entity.h: Fix documentation for media_create_intf_link

The documentation comment was inserted between the return type
and the function name. Reunite the lines.

Signed-off-by: Ian Jamison <ian.dev@arkver.com>
Fixes: db7ee32aa185 ("[media] media-device.h: Improve documentation and update it")
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 012c87f7 02-Mar-2022 Daniel Scally <djrscally@gmail.com>

media: entity: Add support for ancillary links

Add functions to create ancillary links, so that they don't need to
be manually created by users.

Reviewed-by: Laurent Pinchart <laurent.pinchart@idea

media: entity: Add support for ancillary links

Add functions to create ancillary links, so that they don't need to
be manually created by users.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Scally <djrscally@gmail.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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# 443bf23d 24-Feb-2022 Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

media: media-entity: Clarify media_entity_cleanup() usage

Being able to call cleanup functions on objects that haven't been
initialized but whose memory has been zeroed simplifies error handling.
Th

media: media-entity: Clarify media_entity_cleanup() usage

Being able to call cleanup functions on objects that haven't been
initialized but whose memory has been zeroed simplifies error handling.
The media_entity_cleanup() function documentation doesn't tell whether
this is allowed or not, and inspection of its implementation doesn't
provide any clue as the function is currently empty. Update the
documentation to explicitly allow this usage pattern.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

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# 3056a8e9 13-Jan-2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>

media: media-entity: Simplify media_pipeline_start()

The media_pipeline_start() function has two purposes: it constructs a
pipeline by recording the entities that are part of it, gathered from a
gra

media: media-entity: Simplify media_pipeline_start()

The media_pipeline_start() function has two purposes: it constructs a
pipeline by recording the entities that are part of it, gathered from a
graph walk, and validate the media links. The pipeline pointer is stored
in the media_entity structure as part of this process, and the entity's
stream count is increased, to record that the entity is streaming.

When multiple video nodes are present in a pipeline,
media_pipeline_start() is typically called on all of them, with the same
pipeline pointer. This is taken into account in media_pipeline_start()
by skipping validation for entities that are already part of the
pipeline, while returning an error if an entity is part of a different
pipeline.

It turns out that this process is overly complicated. When
media_pipeline_start() is called for the first time, it constructs the
full pipeline, adding all entities and validating all the links.
Subsequent calls to media_pipeline_start() are then nearly no-ops, they
only increase the stream count on the pipeline and on all entities.

The media_entity stream_count field is used for two purposes: checking
if the entity is streaming, and detecting when a call to
media_pipeline_stop() balances needs to reset the entity pipe pointer to
NULL. The former can easily be replaced by a check of the pipe pointer.

Simplify media_pipeline_start() by avoiding the pipeline walk on all
calls but the first one, and drop the media_entity stream_count field.
media_pipeline_stop() is updated accordingly.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[Sakari Ailus: Drop redundant '!= NULL' as discussed]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

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