1 /*
2 * Copyright © 2020 Google, Inc.
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
24 #include "pipe/p_state.h"
25 #include "util/u_prim.h"
26
27 #include "freedreno_batch.h"
28 #include "freedreno_gmem.h"
29
30 #include "fd6_vsc.h"
31
32 /*
33 * Helper util to update expected vsc draw and primitive stream sizes, see
34 * https://github.com/freedreno/freedreno/wiki/Visibility-Stream-Format
35 */
36
37 enum bits_per {
38 byte = 8,
39 dword = 4 * byte,
40 };
41
42 /**
43 * Determine # of bits required to store a given number, see
44 * https://github.com/freedreno/freedreno/wiki/Visibility-Stream-Format#numbers
45 */
46 static unsigned
number_size_bits(unsigned nr)47 number_size_bits(unsigned nr)
48 {
49 unsigned n = util_last_bit(nr);
50 assert(n); /* encoding 0 is not possible */
51 return n + (n - 1);
52 }
53
54 /**
55 * Determine # of bits requred to store a given bitfield, see
56 * https://github.com/freedreno/freedreno/wiki/Visibility-Stream-Format#bitfields
57 */
58 static unsigned
bitfield_size_bits(unsigned n)59 bitfield_size_bits(unsigned n)
60 {
61 return n + 1; /* worst case is always 1 + nr of bits */
62 }
63
64 static unsigned
prim_count(const struct pipe_draw_info * info,const struct pipe_draw_start_count_bias * draw)65 prim_count(const struct pipe_draw_info *info,
66 const struct pipe_draw_start_count_bias *draw)
67 {
68 /* PIPE_PRIM_MAX used internally for RECTLIST blits on 3d pipe: */
69 unsigned vtx_per_prim =
70 (info->mode == PIPE_PRIM_MAX) ? 2 : u_vertices_per_prim(info->mode);
71 return MAX2(1, (draw->count * info->instance_count) / vtx_per_prim);
72 }
73
74 /**
75 * The primitive stream uses a run-length encoding, where each packet contains a
76 * bitfield of bins covered and then the number of primitives which have the
77 * same bitfield. Each packet consists of the following, in order:
78 *
79 * - The (compressed) bitfield of bins covered
80 * - The number of primitives with this bitset
81 * - Checksum
82 *
83 * The worst case would be that each primitive has a different bitmask. In
84 * practice, assuming ever other primitive has a different bitmask still gets us
85 * conservatively large primitive stream sizes. (Ie. 10x what is needed, vs.
86 * 20x)
87 *
88 * https://github.com/freedreno/freedreno/wiki/Visibility-Stream-Format#primitive-streams
89 */
90 static unsigned
primitive_stream_size_bits(const struct pipe_draw_info * info,const struct pipe_draw_start_count_bias * draw,unsigned num_bins)91 primitive_stream_size_bits(const struct pipe_draw_info *info,
92 const struct pipe_draw_start_count_bias *draw,
93 unsigned num_bins)
94 {
95 unsigned num_prims = prim_count(info, draw);
96 unsigned nbits =
97 (bitfield_size_bits(num_bins) /* bitfield of bins covered */
98 + number_size_bits(1) /* number of primitives with this bitset */
99 + 1 /* checksum */
100 ) *
101 DIV_ROUND_UP(num_prims, 2);
102 return align(nbits, dword);
103 }
104
105 /**
106 * Each draw stream packet contains the following:
107 *
108 * - Bin bitfield
109 * - Last instance bit
110 * - If bitfield is empty, the number of draws it is empty for, otherwise
111 * the size of the corresponding primitive stream in DWORD's.
112 * - Checksum
113 *
114 * https://github.com/freedreno/freedreno/wiki/Visibility-Stream-Format#draw-streams
115 */
116 static unsigned
draw_stream_size_bits(const struct pipe_draw_info * info,unsigned num_bins,unsigned prim_strm_bits)117 draw_stream_size_bits(const struct pipe_draw_info *info, unsigned num_bins,
118 unsigned prim_strm_bits)
119 {
120 unsigned ndwords = prim_strm_bits / dword;
121 return (bitfield_size_bits(num_bins) /* bitfield of bins */
122 + 1 /* last-instance-bit */
123 + number_size_bits(ndwords) /* size of corresponding prim strm */
124 + 1 /* checksum */
125 ) *
126 MAX2(1, info->instance_count);
127 }
128
129 void
fd6_vsc_update_sizes(struct fd_batch * batch,const struct pipe_draw_info * info,const struct pipe_draw_start_count_bias * draw)130 fd6_vsc_update_sizes(struct fd_batch *batch, const struct pipe_draw_info *info,
131 const struct pipe_draw_start_count_bias *draw)
132 {
133 if (!batch->num_bins_per_pipe) {
134 batch->num_bins_per_pipe = fd_gmem_estimate_bins_per_pipe(batch);
135
136 /* This is a convenient spot to add the size of the final draw-
137 * stream packet:
138 *
139 * If there are N bins, the final packet, after all the draws are
140 * done, consists of a 1 followed by N + 17 0's, plus a final 1.
141 * This uses the otherwise-unused pattern of a non-empty bitfield
142 * (initial 1) that is nontheless empty (has all 0's)
143 */
144 unsigned final_pkt_sz = 1 + batch->num_bins_per_pipe + 17 + 1;
145 batch->prim_strm_bits = align(final_pkt_sz, dword);
146 }
147
148 unsigned prim_strm_bits =
149 primitive_stream_size_bits(info, draw, batch->num_bins_per_pipe);
150 unsigned draw_strm_bits =
151 draw_stream_size_bits(info, batch->num_bins_per_pipe, prim_strm_bits);
152
153 #if 0
154 mesa_logd("vsc: prim_strm_bits=%d, draw_strm_bits=%d, nb=%u, ic=%u, c=%u, pc=%u (%s)",
155 prim_strm_bits, draw_strm_bits, batch->num_bins_per_pipe,
156 info->instance_count, info->count,
157 (info->count * info->instance_count) /
158 u_vertices_per_prim(info->mode),
159 u_prim_name(info->mode));
160 #endif
161
162 batch->prim_strm_bits += prim_strm_bits;
163 batch->draw_strm_bits += draw_strm_bits;
164 }
165