Add explanation of how to use configfs in order to create a
vimc device with a given topology.
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@xxxxxxxxxxxxx>
---
Documentation/media/v4l-drivers/vimc.dot | 28 ++-
Documentation/media/v4l-drivers/vimc.rst | 240 ++++++++++++++++++++---
2 files changed, 220 insertions(+), 48 deletions(-)
diff --git a/Documentation/media/v4l-drivers/vimc.dot b/Documentation/media/v4l-drivers/vimc.dot
index 57863a13fa39..e3b41ac2bc46 100644
--- a/Documentation/media/v4l-drivers/vimc.dot
+++ b/Documentation/media/v4l-drivers/vimc.dot
@@ -2,21 +2,15 @@
digraph board {
rankdir=TB
- n00000001 [label="{{} | Sensor A\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
- n00000001:port0 -> n00000005:port0 [style=bold]
- n00000001:port0 -> n0000000b [style=bold]
- n00000003 [label="{{} | Sensor B\n/dev/v4l-subdev1 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
- n00000003:port0 -> n00000008:port0 [style=bold]
- n00000003:port0 -> n0000000f [style=bold]
- n00000005 [label="{{<port0> 0} | Debayer A\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
- n00000005:port1 -> n00000017:port0
- n00000008 [label="{{<port0> 0} | Debayer B\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
- n00000008:port1 -> n00000017:port0 [style=dashed]
- n0000000b [label="Raw Capture 0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
- n0000000f [label="Raw Capture 1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
- n00000013 [label="RGB/YUV Input\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
- n00000013 -> n00000017:port0 [style=dashed]
- n00000017 [label="{{<port0> 0} | Scaler\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
- n00000017:port1 -> n0000001a [style=bold]
- n0000001a [label="RGB/YUV Capture\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+ n00000001 [label="cap-deb\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+ n00000005 [label="cap-sen\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+ n00000009 [label="cap-sca\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+ n0000000d [label="{{<port0> 0} | sca\n/dev/v4l-subdev0 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+ n0000000d:port1 -> n00000009 [style=bold]
+ n00000010 [label="{{<port0> 0} | deb\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+ n00000010:port1 -> n00000001 [style=bold]
+ n00000010:port1 -> n0000000d:port0 [style=bold]
+ n00000013 [label="{{} | sen\n/dev/v4l-subdev2 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+ n00000013:port0 -> n00000005 [style=bold]
+ n00000013:port0 -> n00000010:port0 [style=bold]
}
diff --git a/Documentation/media/v4l-drivers/vimc.rst b/Documentation/media/v4l-drivers/vimc.rst
index a582af0509ee..e5636883545f 100644
--- a/Documentation/media/v4l-drivers/vimc.rst
+++ b/Documentation/media/v4l-drivers/vimc.rst
@@ -1,45 +1,225 @@
.. SPDX-License-Identifier: GPL-2.0
+==========================================
The Virtual Media Controller Driver (vimc)
==========================================
-The vimc driver emulates complex video hardware using the V4L2 API and the Media
-API. It has a capture device and three subdevices: sensor, debayer and scaler.
+The vimc driver emulates complex video hardware topologies using the V4L2 API
+and the Media API. It has a capture device and three subdevices:
+sensor, debayer and scaler. It exposes media devices through /dev/mediaX nodes,
+video capture devices through /dev/videoX and sub-devices through /dev/v4l-subdevX.
+
+
+To configure a media device of a given topology, a ConfigFS API is provided.
+
+Configuring a topology through ConfigFS (Experimental)
+======================================================
+
+.. note:: This API is under development and might change in the future.
+
+Mount configfs:
+::
+
+ $ mkdir /configfs
+ $ mount -t configfs none /configfs
+
+When loading the module, you will see a folder named vimc
+::
+
+ $ tree /configfs/
+ /configfs/
+ `-- vimc
+
+Creating a media device
+-----------------------
+
+To create a media device create a new folder under /configfs/vimc/
+
+Example:
+::
+
+ $ mkdir /configfs/vimc/mdev
+ $ tree /configfs/vimc/mdev
+ /configfs/
+ `-- vimc
+ `-- mdev
+ `-- hotplug
+
+Creating entities
+-----------------
+
+To create an entity in the media device's topology, create a folder under
+``/configfs/vimc/<mdev-name>/`` with the following format:
+
+ <entity-type>:<entity-name>
+
+Where <entity-type> is one of the following:
+
+- vimc-sensor
+- vimc-scaler
+- vimc-debayer
+- vimc-capture
+
+Example:
+::
+
+ $ mkdir /configfs/vimc/mdev/vimc-sensor:sen
+ $ mkdir /configfs/vimc/mdev/vimc-capture:cap-sen
+ $ tree /configfs/
+ /configfs/
+ `-- vimc
+ `-- mdev
+ |-- hotplug
+ |-- vimc-capture:cap-sen
+ | `-- pad:sink:0
+ `-- vimc-sensor:sen
+ `-- pad:source:0
+
+Default folders are created under the entity directory for each pad of the entity.
+
+Creating links
+--------------
+
+To create a link between two entities, you should create a directory for the link
+under the source pad of the link and then set it to be a symbolic link to the sink pad:
-Topology
---------
+Example:
+::
+
+ $ mkdir "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-cap"
+ $ ln -s "/configfs/vimc/mdev/vimc-capture:cap-sen/pad:sink:0" "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-cap"
+ $ tree /configfs
+ /configfs
+ `-- vimc
+ `-- mdev
+ |-- hotplug
+ |-- vimc-capture:cap-sen
+ | `-- pad:sink:0
+ `-- vimc-sensor:sen
+ `-- pad:source:0
+ `-- to-cap
+ |-- enabled
+ |-- immutable
+ `-- pad:sink:0 -> ../../../../../vimc/mdev/vimc-capture:cap-sen/pad:sink:0
+
+The `enabled` and `immutable` are two boolean attributes of the link corresponding to the link flags
+
+
+Flag values are described in :ref:`Documentation/media/uapi/mediactl/media-types.rst <media-link-flag>`
+( seek for ``MEDIA_LNK_FL_*``)
+
+1 - Enabled
+ Indicates that the link will be enabled when the media device is created.
+
+3 - Enabled and Immutable
+ Indicates that the link enabled state can't be modified at runtime.
+
+Change an attribute of the link by writing "on" or "1" to set it on , and "off" or "0" to set it off
+
+Example:
+::
+
+ $ echo "on" > /configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-cap/immutable
+
+Activating/Deactivating device
+------------------------------
+
+To activate the device, write one of "plugged", "plug" or "1" to the file
+``/configfs/vimc/<mdev-name>/hotplug``
+
+Example:
+::
+
+ $ echo 1 > /configfs/vimc/mdev/hotplug
+
+You should see a new node ``/dev/mediaX`` in your devfs.
+
+To deactivate the device, write one of "unplugged", "unplug" or "0" to the file
+``/configfs/vimc/<ndev-name>/hotplug``
+
+Example:
+::
+
+ $ echo unplugged > /configfs/vimc/mdev/hotplug
+
+Topology Configuration - Full Example
+-------------------------------------
+
+Here is a full example of a simple topology configuration:
+
+.. code-block:: bash
+
+ # Creating the entities
+ mkdir "/configfs/vimc/mdev"
+ mkdir "/configfs/vimc/mdev/vimc-sensor:sen"
+ mkdir "/configfs/vimc/mdev/vimc-debayer:deb"
+ mkdir "/configfs/vimc/mdev/vimc-scaler:sca"
+ mkdir "/configfs/vimc/mdev/vimc-capture:cap-sca" #/dev/video2
+ mkdir "/configfs/vimc/mdev/vimc-capture:cap-sen" #/dev/video1
+ mkdir "/configfs/vimc/mdev/vimc-capture:cap-deb" #/dev/video0
+
+ # Creating the links
+ #sen -> deb
+ mkdir "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-deb"
+ ln -s "/configfs/vimc/mdev/vimc-debayer:deb/pad:sink:0" "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-deb"
+ echo on > "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-deb/immutable"
+ echo on > "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-deb/enabled"
+
+ #deb -> sca
+ mkdir "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-sca"
+ ln -s "/configfs/vimc/mdev/vimc-scaler:sca/pad:sink:0" "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-sca"
+ echo on > "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-sca/immutable"
+ echo on > "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-sca/enabled"
+
+ #sca -> cap-sca
+ mkdir "/configfs/vimc/mdev/vimc-scaler:sca/pad:source:1/to-cap"
+ ln -s "/configfs/vimc/mdev/vimc-capture:cap-sca/pad:sink:0" "/configfs/vimc/mdev/vimc-scaler:sca/pad:source:1/to-cap"
+ echo on > "/configfs/vimc/mdev/vimc-scaler:sca/pad:source:1/to-cap/immutable"
+ echo on > "/configfs/vimc/mdev/vimc-scaler:sca/pad:source:1/to-cap/enabled"
+
+ #sen -> cap-sen
+ mkdir "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-cap"
+ ln -s "/configfs/vimc/mdev/vimc-capture:cap-sen/pad:sink:0" "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-cap"
+ echo on > "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-cap/immutable"
+ echo on > "/configfs/vimc/mdev/vimc-sensor:sen/pad:source:0/to-cap/enabled"
+
+ #deb -> cap-deb
+ mkdir "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-cap"
+ ln -s "/configfs/vimc/mdev/vimc-capture:cap-deb/pad:sink:0" "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-cap"
+ echo on > "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-cap/immutable"
+ echo on > "/configfs/vimc/mdev/vimc-debayer:deb/pad:source:1/to-cap/enabled"
-The topology is hardcoded, although you could modify it in vimc-core and
-recompile the driver to achieve your own topology. This is the default topology:
.. _vimc_topology_graph:
.. kernel-figure:: vimc.dot
- :alt: Diagram of the default media pipeline topology
+ :alt: Diagram of the configured simple topology in the example
:align: center
- Media pipeline graph on vimc
+ Simple Media pipeline graph on vimc configured through configfs
-Configuring the topology
-~~~~~~~~~~~~~~~~~~~~~~~~
+Configuring the pipeline formats
+================================
-Each subdevice will come with its default configuration (pixelformat, height,
-width, ...). One needs to configure the topology in order to match the
+Each subdevice has a default format configuration (pixelformat, height,
+width, ...). You should configure the formats in order to match the
configuration on each linked subdevice to stream frames through the pipeline.
-If the configuration doesn't match, the stream will fail. The ``v4l-utils``
+If the configuration doesn't match, streaming will fail. The ``v4l-utils``
package is a bundle of user-space applications, that comes with ``media-ctl`` and
-``v4l2-ctl`` that can be used to configure the vimc configuration. This sequence
-of commands fits for the default topology:
+``v4l2-ctl`` that can be used to configure the formats of the entities. This sequence
+of commands fits the simple topology created in the full example of topology configuration:
.. code-block:: bash
- media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
- media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
- media-ctl -d platform:vimc -V '"Sensor B":0[fmt:SBGGR8_1X8/640x480]'
- media-ctl -d platform:vimc -V '"Debayer B":0[fmt:SBGGR8_1X8/640x480]'
- v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
- v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
- v4l2-ctl -z platform:vimc -d "Raw Capture 1" -v pixelformat=BA81
+ media-ctl -d platform:vimc-000 -V '"sen":0[fmt:SBGGR8_1X8/640x480]'
+ media-ctl -d platform:vimc-000 -V '"deb":0[fmt:SBGGR8_1X8/640x480]'
+ media-ctl -d platform:vimc-000 -V '"deb":1[fmt:RGB888_1X24/640x480]'
+ media-ctl -d platform:vimc-000 -V '"sca":0[fmt:RGB888_1X24/640x480]'
+ media-ctl -d platform:vimc-000 -V '"sca":1[fmt:RGB888_1X24/640x480]'
+ v4l2-ctl -z platform:vimc-000 -d "cap-sen" -v pixelformat=BA81
+ v4l2-ctl -z platform:vimc-000 -d "cap-deb" -v pixelformat=RGB3
+ # The default scaling value of the scaler is 3, so need to set its capture accordingly
+ v4l2-ctl -z platform:vimc -d "cap-sca" -v pixelformat=RGB3,width=1920,height=1440
Subdevices
----------
@@ -61,8 +241,8 @@ vimc-debayer:
* 1 Pad source
vimc-scaler:
- Scale up the image by a factor of 3. E.g.: a 640x480 image becomes a
- 1920x1440 image. (this value can be configured, see at
+ Scales up the image by a factor of 3. E.g.: a 640x480 image becomes a
+ 1920x1440 image. (this value can be configured, see
`Module options`_).
Exposes:
@@ -77,12 +257,10 @@ vimc-capture:
* 1 Pad source
- Module options
----------------
-
-Vimc has a few module parameters to configure the driver.
+Module options
+==============
- param=value
+Vimc has 2 module parameters to configure the driver.
* ``sca_mult=<unsigned int>``
@@ -98,10 +276,10 @@ Vimc has a few module parameters to configure the driver.
otherwise the next odd number is considered (the default value is 3).
Source code documentation
--------------------------
+=========================
vimc-streamer
-~~~~~~~~~~~~~
+-------------
.. kernel-doc:: drivers/media/platform/vimc/vimc-streamer.h
:internal:
--
2.20.1
