2 * Copyright (C) 2019 Collabora, Ltd.
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:
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
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
24 * Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
27 #include "pan_resource.h"
28 #include "util/u_format.h"
30 /* Arm FrameBuffer Compression (AFBC) is a lossless compression scheme natively
31 * implemented in Mali GPUs (as well as many display controllers paired with
32 * Mali GPUs, etc). Where possible, Panfrost prefers to use AFBC for both
33 * rendering and texturing. In most cases, this is a performance-win due to a
34 * dramatic reduction in memory bandwidth and cache locality compared to a
37 * AFBC divides the framebuffer into 16x16 tiles (other sizes possible, TODO:
38 * do we need to support this?). So, the width and height each must be aligned
39 * up to 16 pixels. This is inherently good for performance; note that for a 4
40 * byte-per-pixel format like RGBA8888, that means that rows are 16*4=64 byte
41 * aligned, which is the cache-line size.
43 * For each AFBC-compressed resource, there is a single contiguous
44 * (CPU/GPU-shared) buffer. This buffer itself is divided into two parts:
45 * header and body, placed immediately after each other.
47 * The AFBC header contains 16 bytes of metadata per tile.
49 * The AFBC body is the same size as the original linear resource (padded to
50 * the nearest tile). Although the body comes immediately after the header, it
51 * must also be cache-line aligned, so there can sometimes be a bit of padding
52 * between the header and body.
54 * As an example, a 64x64 RGBA framebuffer contains 64/16 = 4 tiles horizontally and
55 * 4 tiles vertically. There are 4*4=16 tiles in total, each containing 16
56 * bytes of metadata, so there is a 16*16=256 byte header. 64x64 is already
57 * tile aligned, so the body is 64*64 * 4 bytes per pixel = 16384 bytes of
60 * From userspace, Panfrost needs to be able to calculate these sizes. It
61 * explicitly does not and can not know the format of the data contained within
62 * this header and body. The GPU has native support for AFBC encode/decode. For
63 * an internal FBO or a framebuffer used for scanout with an AFBC-compatible
64 * winsys/display-controller, the buffer is maintained AFBC throughout flight,
65 * and the driver never needs to know the internal data. For edge cases where
66 * the driver really does need to read/write from the AFBC resource, we
67 * generate a linear staging buffer and use the GPU to blit AFBC<--->linear.
68 * TODO: Implement me. */
70 #define AFBC_TILE_WIDTH 16
71 #define AFBC_TILE_HEIGHT 16
72 #define AFBC_HEADER_BYTES_PER_TILE 16
73 #define AFBC_CACHE_ALIGN 64
75 /* Is it possible to AFBC compress a particular format? Common formats (and
76 * YUV) are compressible. Some obscure formats are not and fallback on linear,
77 * at a performance hit. Also, if you need to disable AFBC entirely in the
78 * driver for debug/profiling, just always return false here. */
81 panfrost_format_supports_afbc(enum pipe_format format
)
83 const struct util_format_description
*desc
=
84 util_format_description(format
);
86 /* sRGB cannot be AFBC, but it can be tiled. TODO: Verify. The blob
87 * does not do AFBC for SRGB8_ALPHA8, but it's not clear why it
88 * shouldn't be able to. */
90 if (desc
->colorspace
== UTIL_FORMAT_COLORSPACE_SRGB
)
93 if (util_format_is_rgba8_variant(desc
))
96 if (format
== PIPE_FORMAT_Z32_UNORM
)
99 /* TODO: AFBC of other formats */
105 panfrost_afbc_header_size(unsigned width
, unsigned height
)
108 unsigned aligned_width
= ALIGN_POT(width
, AFBC_TILE_WIDTH
);
109 unsigned aligned_height
= ALIGN_POT(height
, AFBC_TILE_HEIGHT
);
111 /* Compute size in tiles, rather than pixels */
112 unsigned tile_count_x
= aligned_width
/ AFBC_TILE_WIDTH
;
113 unsigned tile_count_y
= aligned_height
/ AFBC_TILE_HEIGHT
;
114 unsigned tile_count
= tile_count_x
* tile_count_y
;
116 /* Multiply to find the header size */
117 unsigned header_bytes
= tile_count
* AFBC_HEADER_BYTES_PER_TILE
;
120 return ALIGN_POT(header_bytes
, AFBC_CACHE_ALIGN
);