1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 The Virtual Media Controller Driver (vimc) 3 The Virtual Media Controller Driver (vimc)
4 ========================================== 4 ==========================================
5 5
6 The vimc driver emulates complex video hardwar 6 The vimc driver emulates complex video hardware using the V4L2 API and the Media
7 API. It has a capture device and three subdevi 7 API. It has a capture device and three subdevices: sensor, debayer and scaler.
8 8
9 Topology 9 Topology
10 -------- 10 --------
11 11
12 The topology is hardcoded, although you could 12 The topology is hardcoded, although you could modify it in vimc-core and
13 recompile the driver to achieve your own topol 13 recompile the driver to achieve your own topology. This is the default topology:
14 14
15 .. _vimc_topology_graph: 15 .. _vimc_topology_graph:
16 16
17 .. kernel-figure:: vimc.dot 17 .. kernel-figure:: vimc.dot
18 :alt: Diagram of the default media pipel 18 :alt: Diagram of the default media pipeline topology
19 :align: center 19 :align: center
20 20
21 Media pipeline graph on vimc 21 Media pipeline graph on vimc
22 22
23 Configuring the topology 23 Configuring the topology
24 ~~~~~~~~~~~~~~~~~~~~~~~~ 24 ~~~~~~~~~~~~~~~~~~~~~~~~
25 25
26 Each subdevice will come with its default conf 26 Each subdevice will come with its default configuration (pixelformat, height,
27 width, ...). One needs to configure the topolo 27 width, ...). One needs to configure the topology in order to match the
28 configuration on each linked subdevice to stre 28 configuration on each linked subdevice to stream frames through the pipeline.
29 If the configuration doesn't match, the stream 29 If the configuration doesn't match, the stream will fail. The ``v4l-utils``
30 package is a bundle of user-space applications 30 package is a bundle of user-space applications, that comes with ``media-ctl`` and
31 ``v4l2-ctl`` that can be used to configure the 31 ``v4l2-ctl`` that can be used to configure the vimc configuration. This sequence
32 of commands fits for the default topology: 32 of commands fits for the default topology:
33 33
34 .. code-block:: bash 34 .. code-block:: bash
35 35
36 media-ctl -d platform:vimc -V '"Sensor 36 media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
37 media-ctl -d platform:vimc -V '"Debaye 37 media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
38 media-ctl -d platform:vimc -V '"Scaler !! 38 media-ctl -d platform:vimc -V '"Sensor B":0[fmt:SBGGR8_1X8/640x480]'
39 media-ctl -d platform:vimc -V '"Scaler !! 39 media-ctl -d platform:vimc -V '"Debayer B":0[fmt:SBGGR8_1X8/640x480]'
40 media-ctl -d platform:vimc -V '"Scaler !! 40 v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
41 v4l2-ctl -z platform:vimc -d "RGB/YUV <<
42 v4l2-ctl -z platform:vimc -d "Raw Capt 41 v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
>> 42 v4l2-ctl -z platform:vimc -d "Raw Capture 1" -v pixelformat=BA81
43 43
44 Subdevices 44 Subdevices
45 ---------- 45 ----------
46 46
47 Subdevices define the behavior of an entity in 47 Subdevices define the behavior of an entity in the topology. Depending on the
48 subdevice, the entity can have multiple pads o 48 subdevice, the entity can have multiple pads of type source or sink.
49 49
50 vimc-sensor: 50 vimc-sensor:
51 Generates images in several formats us 51 Generates images in several formats using video test pattern generator.
52 Exposes: 52 Exposes:
53 53
54 * 1 Pad source 54 * 1 Pad source
55 55
56 vimc-lens: <<
57 Ancillary lens for a sensor. Supports <<
58 a vimc-sensor using an ancillary link. <<
59 control. <<
60 <<
61 .. code-block:: bash <<
62 <<
63 media-ctl -p <<
64 ... <<
65 - entity 28: Lens A (0 pad, 0 link) <<
66 type V4L2 subdev subty <<
67 device node name /dev/ <<
68 - entity 29: Lens B (0 pad, 0 link) <<
69 type V4L2 subdev subty <<
70 device node name /dev/ <<
71 v4l2-ctl -d /dev/v4l-subdev7 -C focus_ <<
72 focus_absolute: 0 <<
73 <<
74 <<
75 vimc-debayer: 56 vimc-debayer:
76 Transforms images in bayer format into 57 Transforms images in bayer format into a non-bayer format.
77 Exposes: 58 Exposes:
78 59
79 * 1 Pad sink 60 * 1 Pad sink
80 * 1 Pad source 61 * 1 Pad source
81 62
82 vimc-scaler: 63 vimc-scaler:
83 Re-size the image to meet the source p !! 64 Scale up the image by a factor of 3. E.g.: a 640x480 image becomes a
84 pad is configured to 360x480 and the s !! 65 1920x1440 image. (this value can be configured, see at
85 be stretched to fit the source resolut !! 66 `Module options`_).
86 within the vimc limitations (even shri <<
87 Exposes: 67 Exposes:
88 68
89 * 1 Pad sink 69 * 1 Pad sink
90 * 1 Pad source 70 * 1 Pad source
91 71
92 vimc-capture: 72 vimc-capture:
93 Exposes node /dev/videoX to allow user 73 Exposes node /dev/videoX to allow userspace to capture the stream.
94 Exposes: 74 Exposes:
95 75
96 * 1 Pad sink 76 * 1 Pad sink
97 * 1 Pad source 77 * 1 Pad source
98 78
>> 79
99 Module options 80 Module options
100 -------------- 81 --------------
101 82
102 Vimc has a module parameter to configure the d 83 Vimc has a module parameter to configure the driver.
103 84
104 * ``allocator=<unsigned int>`` !! 85 * ``sca_mult=<unsigned int>``
105 <<
106 memory allocator selection, default is <<
107 will be allocated. <<
108 86
109 - 0: vmalloc !! 87 Image size multiplier factor to be used to multiply both width and
110 - 1: dma-contig !! 88 height, so the image size will be ``sca_mult^2`` bigger than the
>> 89 original one. Currently, only supports scaling up (the default value
>> 90 is 3).
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