1/*
2 * Copyright (C) 2019 Collabora, Ltd.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 *
23 * Authors:
24 *   Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
25 */
26
27#include "pan_texture.h"
28
29/* Arm FrameBuffer Compression (AFBC) is a lossless compression scheme natively
30 * implemented in Mali GPUs (as well as many display controllers paired with
31 * Mali GPUs, etc). Where possible, Panfrost prefers to use AFBC for both
32 * rendering and texturing. In most cases, this is a performance-win due to a
33 * dramatic reduction in memory bandwidth and cache locality compared to a
34 * linear resources.
35 *
36 * AFBC divides the framebuffer into 16x16 tiles (other sizes possible, TODO:
37 * do we need to support this?). So, the width and height each must be aligned
38 * up to 16 pixels. This is inherently good for performance; note that for a 4
39 * byte-per-pixel format like RGBA8888, that means that rows are 16*4=64 byte
40 * aligned, which is the cache-line size.
41 *
42 * For each AFBC-compressed resource, there is a single contiguous
43 * (CPU/GPU-shared) buffer. This buffer itself is divided into two parts:
44 * header and body, placed immediately after each other.
45 *
46 * The AFBC header contains 16 bytes of metadata per tile.
47 *
48 * The AFBC body is the same size as the original linear resource (padded to
49 * the nearest tile). Although the body comes immediately after the header, it
50 * must also be cache-line aligned, so there can sometimes be a bit of padding
51 * between the header and body.
52 *
53 * As an example, a 64x64 RGBA framebuffer contains 64/16 = 4 tiles horizontally and
54 * 4 tiles vertically. There are 4*4=16 tiles in total, each containing 16
55 * bytes of metadata, so there is a 16*16=256 byte header. 64x64 is already
56 * tile aligned, so the body is 64*64 * 4 bytes per pixel = 16384 bytes of
57 * body.
58 *
59 * From userspace, Panfrost needs to be able to calculate these sizes. It
60 * explicitly does not and can not know the format of the data contained within
61 * this header and body. The GPU has native support for AFBC encode/decode. For
62 * an internal FBO or a framebuffer used for scanout with an AFBC-compatible
63 * winsys/display-controller, the buffer is maintained AFBC throughout flight,
64 * and the driver never needs to know the internal data. For edge cases where
65 * the driver really does need to read/write from the AFBC resource, we
66 * generate a linear staging buffer and use the GPU to blit AFBC<--->linear.
67 * TODO: Implement me. */
68
69#define AFBC_TILE_WIDTH 16
70#define AFBC_TILE_HEIGHT 16
71#define AFBC_CACHE_ALIGN 64
72
73/* AFBC supports compressing a few canonical formats. Additional formats are
74 * available by using a canonical internal format. Given a PIPE format, find
75 * the canonical AFBC internal format if it exists, or NONE if the format
76 * cannot be compressed. */
77
78enum pipe_format
79panfrost_afbc_format(const struct panfrost_device *dev, enum pipe_format format)
80{
81        /* Don't allow swizzled formats on v7 */
82        switch (format) {
83        case PIPE_FORMAT_B8G8R8A8_UNORM:
84        case PIPE_FORMAT_B8G8R8X8_UNORM:
85        case PIPE_FORMAT_A8R8G8B8_UNORM:
86        case PIPE_FORMAT_X8R8G8B8_UNORM:
87        case PIPE_FORMAT_X8B8G8R8_UNORM:
88        case PIPE_FORMAT_A8B8G8R8_UNORM:
89        case PIPE_FORMAT_B8G8R8_UNORM:
90        case PIPE_FORMAT_B5G6R5_UNORM:
91                if (dev->arch >= 7)
92                        return PIPE_FORMAT_NONE;
93
94                break;
95        default:
96                break;
97        }
98
99        switch (format) {
100        case PIPE_FORMAT_Z16_UNORM:
101                return PIPE_FORMAT_R8G8_UNORM;
102
103        case PIPE_FORMAT_R8G8B8_UNORM:
104        case PIPE_FORMAT_B8G8R8_UNORM:
105                return PIPE_FORMAT_R8G8B8_UNORM;
106
107        case PIPE_FORMAT_R8G8B8A8_UNORM:
108        case PIPE_FORMAT_R8G8B8X8_UNORM:
109        case PIPE_FORMAT_Z24_UNORM_S8_UINT:
110        case PIPE_FORMAT_Z24X8_UNORM:
111        case PIPE_FORMAT_X24S8_UINT:
112        case PIPE_FORMAT_B8G8R8A8_UNORM:
113        case PIPE_FORMAT_B8G8R8X8_UNORM:
114        case PIPE_FORMAT_A8R8G8B8_UNORM:
115        case PIPE_FORMAT_X8R8G8B8_UNORM:
116        case PIPE_FORMAT_X8B8G8R8_UNORM:
117        case PIPE_FORMAT_A8B8G8R8_UNORM:
118                return PIPE_FORMAT_R8G8B8A8_UNORM;
119
120        case PIPE_FORMAT_R5G6B5_UNORM:
121        case PIPE_FORMAT_B5G6R5_UNORM:
122                return PIPE_FORMAT_R5G6B5_UNORM;
123
124        /* TODO: More AFBC formats */
125        default:
126                return PIPE_FORMAT_NONE;
127        }
128}
129
130/* A format may be compressed as AFBC if it has an AFBC internal format */
131
132bool
133panfrost_format_supports_afbc(const struct panfrost_device *dev, enum pipe_format format)
134{
135        return panfrost_afbc_format(dev, format) != PIPE_FORMAT_NONE;
136}
137
138unsigned
139panfrost_afbc_header_size(unsigned width, unsigned height)
140{
141        /* Align to tile */
142        unsigned aligned_width  = ALIGN_POT(width,  AFBC_TILE_WIDTH);
143        unsigned aligned_height = ALIGN_POT(height, AFBC_TILE_HEIGHT);
144
145        /* Compute size in tiles, rather than pixels */
146        unsigned tile_count_x = aligned_width  / AFBC_TILE_WIDTH;
147        unsigned tile_count_y = aligned_height / AFBC_TILE_HEIGHT;
148        unsigned tile_count = tile_count_x * tile_count_y;
149
150        /* Multiply to find the header size */
151        unsigned header_bytes = tile_count * AFBC_HEADER_BYTES_PER_TILE;
152
153        /* Align and go */
154        return ALIGN_POT(header_bytes, AFBC_CACHE_ALIGN);
155
156}
157
158/* The lossless colour transform (AFBC_FORMAT_MOD_YTR) requires RGB. */
159
160bool
161panfrost_afbc_can_ytr(enum pipe_format format)
162{
163        const struct util_format_description *desc =
164                util_format_description(format);
165
166        /* YTR is only defined for RGB(A) */
167        if (desc->nr_channels != 3 && desc->nr_channels != 4)
168                return false;
169
170        /* The fourth channel if it exists doesn't matter */
171        return desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB;
172}
173