1 .. SPDX-License-Identifier: GPL-2.0
2
3 .. _v4l2-meta-fmt-rk-isp1-stat-3a:
4
5 ************************************************************************************************************************
6 V4L2_META_FMT_RK_ISP1_PARAMS ('rk1p'), V4L2_META_FMT_RK_ISP1_STAT_3A ('rk1s'), V4L2_META_FMT_RK_ISP1_EXT_PARAMS ('rk1e')
7 ************************************************************************************************************************
8
9 ========================
10 Configuration parameters
11 ========================
12
13 The configuration of the RkISP1 ISP is performed by userspace by providing
14 parameters for the ISP to the driver using the :c:type:`v4l2_meta_format`
15 interface.
16
17 There are two methods that allow to configure the ISP, the `fixed parameters`
18 configuration format and the `extensible parameters` configuration
19 format.
20
21 .. _v4l2-meta-fmt-rk-isp1-params:
22
23 Fixed parameters configuration format
24 =====================================
25
26 When using the fixed configuration format, parameters are passed to the
27 :ref:`rkisp1_params <rkisp1_params>` metadata output video node, using
28 the `V4L2_META_FMT_RK_ISP1_PARAMS` meta format.
29
30 The buffer contains a single instance of the C structure
31 :c:type:`rkisp1_params_cfg` defined in ``rkisp1-config.h``. So the structure can
32 be obtained from the buffer by:
33
34 .. code-block:: c
35
36 struct rkisp1_params_cfg *params = (struct rkisp1_params_cfg*) buffer;
37
38 This method supports a subset of the ISP features only, new applications should
39 use the extensible parameters method.
40
41 .. _v4l2-meta-fmt-rk-isp1-ext-params:
42
43 Extensible parameters configuration format
44 ==========================================
45
46 When using the extensible configuration format, parameters are passed to the
47 :ref:`rkisp1_params <rkisp1_params>` metadata output video node, using
48 the `V4L2_META_FMT_RK_ISP1_EXT_PARAMS` meta format.
49
50 The buffer contains a single instance of the C structure
51 :c:type:`rkisp1_ext_params_cfg` defined in ``rkisp1-config.h``. The
52 :c:type:`rkisp1_ext_params_cfg` structure is designed to allow userspace to
53 populate the data buffer with only the configuration data for the ISP blocks it
54 intends to configure. The extensible parameters format design allows developers
55 to define new block types to support new configuration parameters, and defines a
56 versioning scheme so that it can be extended and versioned without breaking
57 compatibility with existing applications.
58
59 For these reasons, this configuration method is preferred over the `fixed
60 parameters` format alternative.
61
62 .. rkisp1_stat_buffer
63
64 ===========================
65 3A and histogram statistics
66 ===========================
67
68 The ISP1 device collects different statistics over an input Bayer frame.
69 Those statistics are obtained from the :ref:`rkisp1_stats <rkisp1_stats>`
70 metadata capture video node,
71 using the :c:type:`v4l2_meta_format` interface. The buffer contains a single
72 instance of the C structure :c:type:`rkisp1_stat_buffer` defined in
73 ``rkisp1-config.h``. So the structure can be obtained from the buffer by:
74
75 .. code-block:: c
76
77 struct rkisp1_stat_buffer *stats = (struct rkisp1_stat_buffer*) buffer;
78
79 The statistics collected are Exposure, AWB (Auto-white balance), Histogram and
80 AF (Auto-focus). See :c:type:`rkisp1_stat_buffer` for details of the statistics.
81
82 The 3A statistics and configuration parameters described here are usually
83 consumed and produced by dedicated user space libraries that comprise the
84 important tuning tools using software control loop.
85
86 rkisp1 uAPI data types
87 ======================
88
89 .. kernel-doc:: include/uapi/linux/rkisp1-config.h
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