src/gallium/drivers/r300/r300_hyperz.c

   1 /*
   2  * Copyright 2008 Corbin Simpson <MostAwesomeDude@gmail.com>
   3  * Copyright 2009 Marek Olšák <maraeo@gmail.com>
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * on the rights to use, copy, modify, merge, publish, distribute, sub
   9  * license, and/or sell copies of the Software, and to permit persons to whom
  10  * the Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
  20  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  21  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  22  * USE OR OTHER DEALINGS IN THE SOFTWARE. */
  23
  24 #include "r300_context.h"
  25 #include "r300_hyperz.h"
  26 #include "r300_reg.h"
  27 #include "r300_fs.h"
  28
  29 /*****************************************************************************/
  30 /* The HyperZ setup                                                          */
  31 /*****************************************************************************/
  32
  33 static void r300_update_hyperz(struct r300_context* r300)
  34 {
  35     struct r300_hyperz_state *z =
  36         (struct r300_hyperz_state*)r300->hyperz_state.state;
  37
  38     z->zb_bw_cntl = 0;
  39     z->sc_hyperz = R300_SC_HYPERZ_ADJ_2;
  40
  41     if (r300->cbzb_clear)
  42         z->zb_bw_cntl |= R300_ZB_CB_CLEAR_CACHE_LINE_WRITE_ONLY;
  43 }
  44
  45 /*****************************************************************************/
  46 /* The ZTOP state                                                            */
  47 /*****************************************************************************/
  48
  49 static boolean r300_dsa_writes_stencil(
  50         struct pipe_stencil_state *s)
  51 {
  52     return s->enabled && s->writemask &&
  53            (s->fail_op  != PIPE_STENCIL_OP_KEEP ||
  54             s->zfail_op != PIPE_STENCIL_OP_KEEP ||
  55             s->zpass_op != PIPE_STENCIL_OP_KEEP);
  56 }
  57
  58 static boolean r300_dsa_writes_depth_stencil(
  59         struct pipe_depth_stencil_alpha_state *dsa)
  60 {
  61     /* We are interested only in the cases when a depth or stencil value
  62      * can be changed. */
  63
  64     if (dsa->depth.enabled && dsa->depth.writemask &&
  65         dsa->depth.func != PIPE_FUNC_NEVER)
  66         return TRUE;
  67
  68     if (r300_dsa_writes_stencil(&dsa->stencil[0]) ||
  69         r300_dsa_writes_stencil(&dsa->stencil[1]))
  70         return TRUE;
  71
  72     return FALSE;
  73 }
  74
  75 static boolean r300_dsa_alpha_test_enabled(
  76         struct pipe_depth_stencil_alpha_state *dsa)
  77 {
  78     /* We are interested only in the cases when alpha testing can kill
  79      * a fragment. */
  80
  81     return dsa->alpha.enabled && dsa->alpha.func != PIPE_FUNC_ALWAYS;
  82 }
  83
  84 static void r300_update_ztop(struct r300_context* r300)
  85 {
  86     struct r300_ztop_state* ztop_state =
  87         (struct r300_ztop_state*)r300->ztop_state.state;
  88     uint32_t old_ztop = ztop_state->z_buffer_top;
  89
  90     /* This is important enough that I felt it warranted a comment.
  91      *
  92      * According to the docs, these are the conditions where ZTOP must be
  93      * disabled:
  94      * 1) Alpha testing enabled
  95      * 2) Texture kill instructions in fragment shader
  96      * 3) Chroma key culling enabled
  97      * 4) W-buffering enabled
  98      *
  99      * The docs claim that for the first three cases, if no ZS writes happen,
 100      * then ZTOP can be used.
 101      *
 102      * (3) will never apply since we do not support chroma-keyed operations.
 103      * (4) will need to be re-examined (and this comment updated) if/when
 104      * Hyper-Z becomes supported.
 105      *
 106      * Additionally, the following conditions require disabled ZTOP:
 107      * 5) Depth writes in fragment shader
 108      * 6) Outstanding occlusion queries
 109      *
 110      * This register causes stalls all the way from SC to CB when changed,
 111      * but it is buffered on-chip so it does not hurt to write it if it has
 112      * not changed.
 113      *
 114      * ~C.
 115      */
 116
 117     /* ZS writes */
 118     if (r300_dsa_writes_depth_stencil(r300->dsa_state.state) &&
 119            (r300_dsa_alpha_test_enabled(r300->dsa_state.state) ||  /* (1) */
 120             r300_fs(r300)->shader->info.uses_kill)) {              /* (2) */
 121         ztop_state->z_buffer_top = R300_ZTOP_DISABLE;
 122     } else if (r300_fragment_shader_writes_depth(r300_fs(r300))) { /* (5) */
 123         ztop_state->z_buffer_top = R300_ZTOP_DISABLE;
 124     } else if (r300->query_current) {                              /* (6) */
 125         ztop_state->z_buffer_top = R300_ZTOP_DISABLE;
 126     } else {
 127         ztop_state->z_buffer_top = R300_ZTOP_ENABLE;
 128     }
 129
 130     if (ztop_state->z_buffer_top != old_ztop)
 131         r300->ztop_state.dirty = TRUE;
 132 }
 133
 134 void r300_update_hyperz_state(struct r300_context* r300)
 135 {
 136     r300_update_ztop(r300);
 137     if (r300->hyperz_state.dirty) {
 138         r300_update_hyperz(r300);
 139     }
 140 }