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 '"Scaler":0[fmt:RGB888_1X24/640x480]'
39 media-ctl -d platform:vimc -V '"Scaler 39 media-ctl -d platform:vimc -V '"Scaler":0[crop:(100,50)/400x150]'
40 media-ctl -d platform:vimc -V '"Scaler 40 media-ctl -d platform:vimc -V '"Scaler":1[fmt:RGB888_1X24/300x700]'
41 v4l2-ctl -z platform:vimc -d "RGB/YUV 41 v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=300,height=700
42 v4l2-ctl -z platform:vimc -d "Raw Capt 42 v4l2-ctl -z platform:vimc -d "Raw Capture 0" -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: 56 vimc-lens:
57 Ancillary lens for a sensor. Supports 57 Ancillary lens for a sensor. Supports auto focus control. Linked to
58 a vimc-sensor using an ancillary link. 58 a vimc-sensor using an ancillary link. The lens supports FOCUS_ABSOLUTE
59 control. 59 control.
60 60
61 .. code-block:: bash 61 .. code-block:: bash
62 62
63 media-ctl -p 63 media-ctl -p
64 ... 64 ...
65 - entity 28: Lens A (0 pad, 0 link) 65 - entity 28: Lens A (0 pad, 0 link)
66 type V4L2 subdev subty 66 type V4L2 subdev subtype Lens flags 0
67 device node name /dev/ 67 device node name /dev/v4l-subdev6
68 - entity 29: Lens B (0 pad, 0 link) 68 - entity 29: Lens B (0 pad, 0 link)
69 type V4L2 subdev subty 69 type V4L2 subdev subtype Lens flags 0
70 device node name /dev/ 70 device node name /dev/v4l-subdev7
71 v4l2-ctl -d /dev/v4l-subdev7 -C focus_ 71 v4l2-ctl -d /dev/v4l-subdev7 -C focus_absolute
72 focus_absolute: 0 72 focus_absolute: 0
73 73
74 74
75 vimc-debayer: 75 vimc-debayer:
76 Transforms images in bayer format into 76 Transforms images in bayer format into a non-bayer format.
77 Exposes: 77 Exposes:
78 78
79 * 1 Pad sink 79 * 1 Pad sink
80 * 1 Pad source 80 * 1 Pad source
81 81
82 vimc-scaler: 82 vimc-scaler:
83 Re-size the image to meet the source p 83 Re-size the image to meet the source pad resolution. E.g.: if the sync
84 pad is configured to 360x480 and the s 84 pad is configured to 360x480 and the source to 1280x720, the image will
85 be stretched to fit the source resolut 85 be stretched to fit the source resolution. Works for any resolution
86 within the vimc limitations (even shri 86 within the vimc limitations (even shrinking the image if necessary).
87 Exposes: 87 Exposes:
88 88
89 * 1 Pad sink 89 * 1 Pad sink
90 * 1 Pad source 90 * 1 Pad source
91 91
92 vimc-capture: 92 vimc-capture:
93 Exposes node /dev/videoX to allow user 93 Exposes node /dev/videoX to allow userspace to capture the stream.
94 Exposes: 94 Exposes:
95 95
96 * 1 Pad sink 96 * 1 Pad sink
97 * 1 Pad source 97 * 1 Pad source
98 98
99 Module options 99 Module options
100 -------------- 100 --------------
101 101
102 Vimc has a module parameter to configure the d 102 Vimc has a module parameter to configure the driver.
103 103
104 * ``allocator=<unsigned int>`` 104 * ``allocator=<unsigned int>``
105 105
106 memory allocator selection, default is 106 memory allocator selection, default is 0. It specifies the way buffers
107 will be allocated. 107 will be allocated.
108 108
109 - 0: vmalloc 109 - 0: vmalloc
110 - 1: dma-contig 110 - 1: dma-contig
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