src/panfrost/lib/pan_scoreboard.c

   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  */
  24
  25 #include <string.h>
  26 #include "pan_scoreboard.h"
  27 #include "pan_device.h"
  28 #include "panfrost-quirks.h"
  29
  30 /*
  31  * There are various types of Mali jobs:
  32  *
  33  *  - WRITE_VALUE: generic write primitive, used to zero tiler field
  34  *  - VERTEX: runs a vertex shader
  35  *  - TILER: runs tiling and sets up a fragment shader
  36  *  - FRAGMENT: runs fragment shaders and writes out
  37  *  - COMPUTE: runs a compute shader
  38  *  - FUSED: vertex+tiler fused together, implicit intradependency (Bifrost)
  39  *  - GEOMETRY: runs a geometry shader (unimplemented)
  40  *  - CACHE_FLUSH: unseen in the wild, theoretically cache flush
  41  *
  42  * In between a full batch and a single Mali job is the "job chain", a series
  43  * of Mali jobs together forming a linked list. Within the job chain, each Mali
  44  * job can set (up to) two dependencies on other earlier jobs in the chain.
  45  * This dependency graph forms a scoreboard. The general idea of a scoreboard
  46  * applies: when there is a data dependency of job B on job A, job B sets one
  47  * of its dependency indices to job A, ensuring that job B won't start until
  48  * job A finishes.
  49  *
  50  * More specifically, here are a set of rules:
  51  *
  52  * - A write value job must appear if and only if there is at least one tiler
  53  *   job, and tiler jobs must depend on it.
  54  *
  55  * - Vertex jobs and tiler jobs are independent.
  56  *
  57  * - A tiler job must have a dependency on its data source. If it's getting
  58  *   data from a vertex job, it depends on the vertex job. If it's getting data
  59  *   from software, this is null.
  60  *
  61  * - Tiler jobs must depend on the write value job (chained or otherwise).
  62  *
  63  * - Tiler jobs must be strictly ordered. So each tiler job must depend on the
  64  *   previous job in the chain.
  65  *
  66  * - Jobs linking via next_job has no bearing on order of execution, rather it
  67  *   just establishes the linked list of jobs, EXCEPT:
  68  *
  69  * - A job's dependencies must appear earlier in the linked list (job chain).
  70  *
  71  * Justification for each rule:
  72  *
  73  * - Write value jobs are used to write a zero into a magic tiling field, which
  74  *   enables tiling to work. If tiling occurs, they are needed; if it does not,
  75  *   we cannot emit them since then tiling partially occurs and it's bad.
  76  *
  77  * - The hardware has no notion of a "vertex/tiler job" (at least not our
  78  *   hardware -- other revs have fused jobs, but --- crap, this just got even
  79  *   more complicated). They are independent units that take in data, process
  80  *   it, and spit out data.
  81  *
  82  * - Any job must depend on its data source, in fact, or risk a
  83  *   read-before-write hazard. Tiler jobs get their data from vertex jobs, ergo
  84  *   tiler jobs depend on the corresponding vertex job (if it's there).
  85  *
  86  * - The tiler is not thread-safe; this dependency prevents race conditions
  87  *   between two different jobs trying to write to the tiler outputs at the
  88  *   same time.
  89  *
  90  * - Internally, jobs are scoreboarded; the next job fields just form a linked
  91  *   list to allow the jobs to be read in; the execution order is from
  92  *   resolving the dependency fields instead.
  93  *
  94  * - The hardware cannot set a dependency on a job it doesn't know about yet,
  95  *   and dependencies are processed in-order of the next job fields.
  96  *
  97  */
  98
  99 /* Generates, uploads, and queues a a new job. All fields are written in order
 100  * except for next_job accounting (TODO: Should we be clever and defer the
 101  * upload of the header here until next job to keep the access pattern totally
 102  * linear? Or is that just a micro op at this point?). Returns the generated
 103  * index for dep management.
 104  *
 105  * Inject is used to inject a job at the front, for wallpapering. If you are
 106  * not wallpapering and set this, dragons will eat you. */
 107
 108 unsigned
 109 panfrost_new_job(
 110                 struct pan_pool *pool,
 111                 struct pan_scoreboard *scoreboard,
 112                 enum mali_job_type type,
 113                 bool barrier,
 114                 unsigned local_dep,
 115                 void *payload, size_t payload_size,
 116                 bool inject)
 117 {
 118         unsigned global_dep = 0;
 119
 120         if (type == MALI_JOB_TYPE_TILER) {
 121                 /* Tiler jobs must be chained, and on Midgard, the first tiler
 122                  * job must depend on the write value job, whose index we
 123                  * reserve now */
 124
 125                 if (scoreboard->tiler_dep)
 126                         global_dep = scoreboard->tiler_dep;
 127                 else if (!(pool->dev->quirks & IS_BIFROST)) {
 128                         scoreboard->write_value_index = ++scoreboard->job_index;
 129                         global_dep = scoreboard->write_value_index;
 130                 }
 131         }
 132
 133         /* Assign the index */
 134         unsigned index = ++scoreboard->job_index;
 135
 136         struct mali_job_descriptor_header job = {
 137                 .job_descriptor_size = 1,
 138                 .job_type = type,
 139                 .job_barrier = barrier,
 140                 .job_index = index,
 141                 .job_dependency_index_1 = local_dep,
 142                 .job_dependency_index_2 = global_dep,
 143         };
 144
 145         if (inject)
 146                 job.next_job = scoreboard->first_job;
 147
 148         struct panfrost_transfer transfer =
 149                 panfrost_pool_alloc_aligned(pool, sizeof(job) + payload_size, 64);
 150         memcpy(transfer.cpu, &job, sizeof(job));
 151         memcpy(transfer.cpu + sizeof(job), payload, payload_size);
 152
 153         if (inject) {
 154                 scoreboard->first_job = transfer.gpu;
 155                 return index;
 156         }
 157
 158         /* Form a chain */
 159         if (type == MALI_JOB_TYPE_TILER)
 160                 scoreboard->tiler_dep = index;
 161
 162         if (scoreboard->prev_job)
 163                 scoreboard->prev_job->next_job = transfer.gpu;
 164         else
 165                 scoreboard->first_job = transfer.gpu;
 166
 167         scoreboard->prev_job = (struct mali_job_descriptor_header *) transfer.cpu;
 168         return index;
 169 }
 170
 171 /* Generates a write value job, used to initialize the tiler structures. Note
 172  * this is called right before frame submission. */
 173
 174 void
 175 panfrost_scoreboard_initialize_tiler(struct pan_pool *pool,
 176                 struct pan_scoreboard *scoreboard,
 177                 mali_ptr polygon_list)
 178 {
 179         /* Check if we even need tiling */
 180         if (pool->dev->quirks & IS_BIFROST || !scoreboard->tiler_dep)
 181                 return;
 182
 183         /* Okay, we do. Let's generate it. We'll need the job's polygon list
 184          * regardless of size. */
 185
 186         struct mali_job_descriptor_header job = {
 187                 .job_type = MALI_JOB_TYPE_WRITE_VALUE,
 188                 .job_index = scoreboard->write_value_index,
 189                 .job_descriptor_size = 1,
 190                 .next_job = scoreboard->first_job
 191         };
 192
 193         struct mali_payload_write_value payload = {
 194                 .address = polygon_list,
 195                 .value_descriptor = MALI_WRITE_VALUE_ZERO,
 196         };
 197
 198         struct panfrost_transfer transfer = panfrost_pool_alloc_aligned(pool, sizeof(job) + sizeof(payload), 64);
 199         memcpy(transfer.cpu, &job, sizeof(job));
 200         memcpy(transfer.cpu + sizeof(job), &payload, sizeof(payload));
 201
 202         scoreboard->first_job = transfer.gpu;
 203 }