1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 DW100 dewarp driver 3 DW100 dewarp driver
4 =================== 4 ===================
5 5
6 The Vivante DW100 Dewarp Processor IP core fou 6 The Vivante DW100 Dewarp Processor IP core found on i.MX8MP SoC applies a
7 programmable geometrical transformation on the 7 programmable geometrical transformation on the input image to correct distortion
8 introduced by lenses. 8 introduced by lenses.
9 9
10 The transformation function is exposed by the 10 The transformation function is exposed by the hardware as a grid map with 16x16
11 pixel macroblocks indexed using X, Y vertex co 11 pixel macroblocks indexed using X, Y vertex coordinates.
12 :: 12 ::
13 13
14 Image width 14 Image width
15 <---------------------------------- 15 <--------------------------------------->
16 16
17 ^ .-------.-------.-------.-------.-- 17 ^ .-------.-------.-------.-------.-------.
18 | | 16x16 | | | | 18 | | 16x16 | | | | |
19 I | | pixel | | | | 19 I | | pixel | | | | |
20 m | | block | | | | 20 m | | block | | | | |
21 a | .-------.-------.-------.-------.-- 21 a | .-------.-------.-------.-------.-------.
22 g | | | | | | 22 g | | | | | | |
23 e | | | | | | 23 e | | | | | | |
24 | | | | | | 24 | | | | | | |
25 h | .-------.-------.-------.-------.-- 25 h | .-------.-------.-------.-------.-------.
26 e | | | | | | 26 e | | | | | | |
27 i | | | | | | 27 i | | | | | | |
28 g | | | | | | 28 g | | | | | | |
29 h | .-------.-------.-------.-------.-- 29 h | .-------.-------.-------.-------.-------.
30 t | | | | | | 30 t | | | | | | |
31 | | | | | | 31 | | | | | | |
32 | | | | | | 32 | | | | | | |
33 v '-------'-------'-------'-------'-- 33 v '-------'-------'-------'-------'-------'
34 34
35 Grid of Image Blocks for Dewarping 35 Grid of Image Blocks for Dewarping Map
36 36
37 37
38 Each x, y coordinate register uses 16 bits to 38 Each x, y coordinate register uses 16 bits to record the coordinate address in
39 an unsigned 12.4 fixed point format (UQ12.4). 39 an unsigned 12.4 fixed point format (UQ12.4).
40 :: 40 ::
41 41
42 .----------------------.--------..-------- 42 .----------------------.--------..----------------------.--------.
43 | 31~20 | 19~16 || 43 | 31~20 | 19~16 || 15~4 | 3~0 |
44 | (integer) | (frac) || ( 44 | (integer) | (frac) || (integer) | (frac) |
45 '----------------------'--------''-------- 45 '----------------------'--------''----------------------'--------'
46 <-------------------------------><-------- 46 <-------------------------------><------------------------------->
47 Y coordinate 47 Y coordinate X coordinate
48 48
49 Remap Register Layo 49 Remap Register Layout
50 50
51 The dewarping map is set from applications usi 51 The dewarping map is set from applications using the
52 V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP cont 52 V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP control. The control contains
53 an array of u32 values storing (x, y) destinat 53 an array of u32 values storing (x, y) destination coordinates for each
54 vertex of the grid. The x coordinate is stored 54 vertex of the grid. The x coordinate is stored in the 16 LSBs and the y
55 coordinate in the 16 MSBs. 55 coordinate in the 16 MSBs.
56 56
57 The number of elements in the array must match 57 The number of elements in the array must match the image size:
58 58
59 .. code-block:: C 59 .. code-block:: C
60 60
61 elems = (DIV_ROUND_UP(width, 16) + 1) * (D 61 elems = (DIV_ROUND_UP(width, 16) + 1) * (DIV_ROUND_UP(height, 16) + 1);
62 62
63 If the control has not been set by the applica 63 If the control has not been set by the application, the driver uses an identity
64 map. 64 map.
65 65
66 More details on the DW100 hardware operations 66 More details on the DW100 hardware operations can be found in
67 *chapter 13.15 DeWarp* of IMX8MP_ reference ma 67 *chapter 13.15 DeWarp* of IMX8MP_ reference manual.
68 68
69 The Vivante DW100 m2m driver implements the fo 69 The Vivante DW100 m2m driver implements the following driver-specific control:
70 70
71 ``V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP (_ 71 ``V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP (__u32 array)``
72 Specifies to DW100 driver its dewarping ma 72 Specifies to DW100 driver its dewarping map (aka LUT) blob as described in
73 *chapter 13.15.2.3 Dewarping Remap* of IMX 73 *chapter 13.15.2.3 Dewarping Remap* of IMX8MP_ reference manual as an U32
74 dynamic array. The image is divided into m 74 dynamic array. The image is divided into many small 16x16 blocks. If the
75 width/height of the image is not divisible 75 width/height of the image is not divisible by 16, the size of the
76 rightmost/bottommost block is the remainde 76 rightmost/bottommost block is the remainder. The dewarping map only saves
77 the vertex coordinates of the block. The d 77 the vertex coordinates of the block. The dewarping grid map is comprised of
78 vertex coordinates for x and y. Each x, y 78 vertex coordinates for x and y. Each x, y coordinate register uses 16 bits
79 (UQ12.4) to record the coordinate address, 79 (UQ12.4) to record the coordinate address, with the Y coordinate in the
80 upper bits and X in the lower bits. The dr 80 upper bits and X in the lower bits. The driver modifies the dimensions of
81 this control when the sink format is chang 81 this control when the sink format is changed, to reflect the new input
82 resolution. 82 resolution.
83 83
84 .. _IMX8MP: https://www.nxp.com/webapp/Downloa 84 .. _IMX8MP: https://www.nxp.com/webapp/Download?colCode=IMX8MPRM
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