2 * Copyright (C) 2019 Collabora
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 */
104 /* AFBC is enabled on a per-resource basis (AFBC enabling is theoretically
105 * indepdent between color buffers and depth/stencil). To enable, we allocate
106 * the AFBC metadata buffer and mark that it is enabled. We do -not- actually
107 * edit the fragment job here. This routine should be called ONCE per
108 * AFBC-compressed buffer, rather than on every frame. */
111 panfrost_enable_afbc(struct panfrost_context
*ctx
, struct panfrost_resource
*rsrc
, bool ds
)
113 struct pipe_context
*gallium
= (struct pipe_context
*) ctx
;
114 struct panfrost_screen
*screen
= pan_screen(gallium
->screen
);
116 unsigned width
= rsrc
->base
.width0
;
117 unsigned height
= rsrc
->base
.height0
;
118 unsigned bytes_per_pixel
= util_format_get_blocksize(rsrc
->base
.format
);
121 unsigned aligned_width
= ALIGN(width
, AFBC_TILE_WIDTH
);
122 unsigned aligned_height
= ALIGN(height
, AFBC_TILE_HEIGHT
);
124 /* Compute size in tiles, rather than pixels */
125 unsigned tile_count_x
= aligned_width
/ AFBC_TILE_WIDTH
;
126 unsigned tile_count_y
= aligned_height
/ AFBC_TILE_HEIGHT
;
127 unsigned tile_count
= tile_count_x
* tile_count_y
;
129 unsigned header_bytes
= tile_count
* AFBC_HEADER_BYTES_PER_TILE
;
130 unsigned header_size
= ALIGN(header_bytes
, AFBC_CACHE_ALIGN
);
132 /* The stride is a normal stride, but aligned */
133 unsigned unaligned_stride
= aligned_width
* bytes_per_pixel
;
134 unsigned stride
= ALIGN(unaligned_stride
, AFBC_CACHE_ALIGN
);
136 /* Compute the entire buffer size */
137 unsigned body_size
= stride
* aligned_height
;
138 unsigned buffer_size
= header_size
+ body_size
;
140 /* Allocate the AFBC slab itself, large enough to hold the above */
141 panfrost_drm_allocate_slab(screen
, &rsrc
->bo
->afbc_slab
,
142 ALIGN(buffer_size
, 4096) / 4096,
145 /* Compressed textured reads use a tagged pointer to the metadata */
146 rsrc
->bo
->layout
= PAN_AFBC
;
147 rsrc
->bo
->gpu
= rsrc
->bo
->afbc_slab
.gpu
| (ds
? 0 : 1);
148 rsrc
->bo
->cpu
= rsrc
->bo
->afbc_slab
.cpu
;
149 rsrc
->bo
->gem_handle
= rsrc
->bo
->afbc_slab
.gem_handle
;
150 rsrc
->bo
->afbc_metadata_size
= header_size
;