1 .. SPDX-License-Identifier: GPL-2.0
2
3 ==============================================
4 Raspberry Pi PiSP Back End Memory-to-Memory IS
5 ==============================================
6
7 The PiSP Back End
8 =================
9
10 The PiSP Back End is a memory-to-memory Image
11 image data from DRAM memory and performs image
12 application through the parameters in a config
13 pixel data back to memory through two distinct
14
15 The ISP registers and programming model are do
16 Image Signal Processor (PiSP) Specification do
17
18 The PiSP Back End ISP processes images in tile
19 tessellation and the computation of low-level
20 realized by a free software library called `li
21 <https://github.com/raspberrypi/libpisp>`_.
22
23 The full image processing pipeline, which invo
24 an image sensor through a MIPI CSI-2 compatibl
25 in DRAM memory and processing them in the PiSP
26 by an application is implemented in `libcamera
27 part of the Raspberry Pi platform support.
28
29 The pisp-be driver
30 ==================
31
32 The Raspberry Pi PiSP Back End (pisp-be) drive
33 drivers/media/platform/raspberrypi/pisp-be. It
34 a number of video capture and output devices,
35 a subdevice for the ISP that connects the vide
36 realized using the `Media Controller (MC) API`
37
38 The media topology registered by the `pisp-be`
39
40 .. _pips-be-topology:
41
42 .. kernel-figure:: raspberrypi-pisp-be.dot
43 :alt: Diagram of the default media pipel
44 :align: center
45
46
47 The media graph registers the following video
48
49 - pispbe-input: output device for images to be
50 processing.
51 - pispbe-tdn_input: output device for temporal
52 - pispbe-stitch_input: output device for image
53 - pispbe-output0: first capture device for pro
54 - pispbe-output1: second capture device for pr
55 - pispbe-tdn_output: capture device for tempor
56 - pispbe-stitch_output: capture device for ima
57 - pispbe-config: output device for ISP configu
58
59 pispbe-input
60 ------------
61
62 Images to be processed by the ISP are queued t
63 node. For a list of image formats supported as
64 `Raspberry Pi Image Signal Processor (PiSP) Sp
65
66 pispbe-tdn_input, pispbe-tdn_output
67 -----------------------------------
68
69 The `pispbe-tdn_input` output video device rec
70 the temporal denoise block which are captured
71 capture video device. Userspace is responsible
72 devices, and ensuring that buffers completed o
73 input.
74
75 pispbe-stitch_input, pispbe-stitch_output
76 -----------------------------------------
77
78 To realize HDR (high dynamic range) image proc
79 tonemapping blocks are used. The `pispbe-stitc
80 and the `pispbe-stitch_input` receives the pre
81 it along with the current input image. Userspa
82 queues on both devices, and ensuring that buff
83 queued to the input.
84
85 pispbe-output0, pispbe-output1
86 ------------------------------
87
88 The two capture devices write to memory the pi
89
90 pispbe-config
91 -------------
92
93 The `pispbe-config` output video devices recei
94 parameters that define the desired image proce
95
96 The format of the ISP configuration parameter
97 :c:type:`pisp_be_tiles_config` C structure and
98 described in the `Raspberry Pi Image Signal Pr
99 document`_.
100
101 ISP configuration
102 =================
103
104 The ISP configuration is described solely by t
105 buffer. The only parameter that userspace need
106 is the image format on the output and capture
107 the content of the parameters buffer.
108
109 .. _Raspberry Pi Image Signal Processor (PiSP)
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