r300g: implement MSAA

This is not as optimized as r600g - the MSAA compression is missing,
so r300g needs a lot of bandwidth (more than r600g to do the same thing).
However, if the bandwidth is not an issue for you, you can enjoy this
unoptimized MSAA support.
The only other missing optimization for MSAA is the fast color clear.

MSAA is enabled on r500 only, because that's the only GPU family I tested.
That said, MSAA should work on r300 and r400 as well (but you must set
RADEON_MSAA=1 to allow it, then turn MSAA on in your app or set GALLIUM_MSAA=n,
n >= 2, n <= 6)
I will enable the support by default on r300-r400 once someone (other than me)
tests those chipsets with piglit.

The supported modes are 2x, 4x, 6x.

The supported MSAA formats are RGBA8, BGRA8, and RGBA16F (r500 only).
Those 3 formats are used for all GL internal formats.

Tested with piglit. (I have ported all MSAA tests to GL2.1)

1 files changed, 134 insertions, 31 deletions

diff --git a/src/gallium/drivers/r300/r300_emit.c b/src/gallium/drivers/r300/r300_emit.c
index 1b9de40afaa..1700cbb4667 100644
--- a/src/gallium/drivers/r300/r300_emit.c
+++ b/src/gallium/drivers/r300/r300_emit.c
@@ -93,6 +93,13 @@ void r300_emit_dsa_state(struct r300_context* r300, unsigned size, void* state)
         }
     }
 
+    /* Setup alpha-to-coverage. */
+    if (r300->alpha_to_coverage && r300->msaa_enable) {
+        /* Always set 3/6, it improves precision even for 2x and 4x MSAA. */
+        alpha_func |= R300_FG_ALPHA_FUNC_MASK_ENABLE |
+                      R300_FG_ALPHA_FUNC_CFG_3_OF_6;
+    }
+
     OUT_CS_REG(R300_FG_ALPHA_FUNC, alpha_func);
     WRITE_CS_TABLE(fb->zsbuf ? &dsa->cb_begin : dsa->cb_zb_no_readwrite, size-2);
 }
@@ -366,12 +373,16 @@ void r300_emit_aa_state(struct r300_context *r300, unsigned size, void *state)
     OUT_CS_REG(R300_GB_AA_CONFIG, aa->aa_config);
 
     if (aa->dest) {
-        OUT_CS_REG(R300_RB3D_AARESOLVE_OFFSET, aa->dest->offset);
+        OUT_CS_REG_SEQ(R300_RB3D_AARESOLVE_OFFSET, 3);
+        OUT_CS(aa->dest->offset);
+        OUT_CS(aa->dest->pitch & R300_RB3D_AARESOLVE_PITCH_MASK);
+        OUT_CS(R300_RB3D_AARESOLVE_CTL_AARESOLVE_MODE_RESOLVE |
+               R300_RB3D_AARESOLVE_CTL_AARESOLVE_ALPHA_AVERAGE);
         OUT_CS_RELOC(aa->dest);
-        OUT_CS_REG(R300_RB3D_AARESOLVE_PITCH, aa->dest->pitch);
+    } else {
+        OUT_CS_REG(R300_RB3D_AARESOLVE_CTL, 0);
     }
 
-    OUT_CS_REG(R300_RB3D_AARESOLVE_CTL, aa->aaresolve_ctl);
     END_CS;
 }
 
@@ -475,12 +486,85 @@ void r300_emit_hyperz_end(struct r300_context *r300)
     r300_emit_hyperz_state(r300, r300->hyperz_state.size, &z);
 }
 
+#define R300_NIBBLES(x0, y0, x1, y1, x2, y2, d0y, d0x)  \
+    (((x0) & 0xf) | (((y0) & 0xf) << 4) |		   \
+    (((x1) & 0xf) << 8) | (((y1) & 0xf) << 12) |	   \
+    (((x2) & 0xf) << 16) | (((y2) & 0xf) << 20) |	   \
+    (((d0y) & 0xf) << 24) | (((d0x) & 0xf) << 28))
+
+static unsigned r300_get_mspos(int index, unsigned *p)
+{
+    unsigned reg, i, distx, disty, dist;
+
+    if (index == 0) {
+        /* MSPOS0 contains positions for samples 0,1,2 as (X,Y) pairs of nibbles,
+         * followed by a (Y,X) pair containing the minimum distance from the pixel
+         * edge:
+         *     X0, Y0, X1, Y1, X2, Y2, D0_Y, D0_X
+         *
+         * There is a quirk when setting D0_X. The value represents the distance
+         * from the left edge of the pixel quad to the first sample in subpixels.
+         * All values less than eight should use the actual value, but „7‟ should
+         * be used for the distance „8‟. The hardware will convert 7 into 8 internally.
+         */
+        distx = 11;
+        for (i = 0; i < 12; i += 2) {
+            if (p[i] < distx)
+                distx = p[i];
+        }
+
+        disty = 11;
+        for (i = 1; i < 12; i += 2) {
+            if (p[i] < disty)
+                disty = p[i];
+        }
+
+        if (distx == 8)
+            distx = 7;
+
+        reg = R300_NIBBLES(p[0], p[1], p[2], p[3], p[4], p[5], disty, distx);
+    } else {
+        /* MSPOS1 contains positions for samples 3,4,5 as (X,Y) pairs of nibbles,
+         * followed by the minimum distance from the pixel edge (not sure if X or Y):
+         *     X3, Y3, X4, Y4, X5, Y5, D1
+         */
+        dist = 11;
+        for (i = 0; i < 12; i++) {
+            if (p[i] < dist)
+                dist = p[i];
+        }
+
+        reg = R300_NIBBLES(p[6], p[7], p[8], p[9], p[10], p[11], dist, 0);
+    }
+    return reg;
+}
+
 void r300_emit_fb_state_pipelined(struct r300_context *r300,
                                   unsigned size, void *state)
 {
+    /* The sample coordinates are in the range [0,11], because
+     * GB_TILE_CONFIG.SUBPIXEL is set to the 1/12 subpixel precision.
+     *
+     * Some sample coordinates reach to neighboring pixels and should not be used.
+     * (e.g. Y=11)
+     *
+     * The unused samples must be set to the positions of other valid samples. */
+    static unsigned sample_locs_1x[12] = {
+        6,6,  6,6,  6,6,  6,6,  6,6,  6,6
+    };
+    static unsigned sample_locs_2x[12] = {
+        3,9,  9,3,  9,3,  9,3,  9,3,  9,3
+    };
+    static unsigned sample_locs_4x[12] = {
+        4,4,  8,8,  2,10,  10,2,  10,2,  10,2
+    };
+    static unsigned sample_locs_6x[12] = {
+        3,1,  7,3,  11,5,  1,7,  5,9,  9,10
+    };
+
     struct pipe_framebuffer_state* fb =
             (struct pipe_framebuffer_state*)r300->fb_state.state;
-    unsigned i, num_cbufs = fb->nr_cbufs;
+    unsigned i, num_samples, num_cbufs = fb->nr_cbufs;
     unsigned mspos0, mspos1;
     CS_LOCALS(r300);
 
@@ -509,32 +593,28 @@ void r300_emit_fb_state_pipelined(struct r300_context *r300,
 
     /* Multisampling. Depends on framebuffer sample count.
      * These are pipelined regs and as such cannot be moved
-     * to the AA state. */
-    mspos0 = 0x66666666;
-    mspos1 = 0x6666666;
-
-    if (fb->nr_cbufs && fb->cbufs[0]->texture->nr_samples > 1) {
-        /* Subsample placement. These may not be optimal. */
-        switch (fb->cbufs[0]->texture->nr_samples) {
-        case 2:
-            mspos0 = 0x33996633;
-            mspos1 = 0x6666663;
-            break;
-        case 3:
-            mspos0 = 0x33936933;
-            mspos1 = 0x6666663;
-            break;
-        case 4:
-            mspos0 = 0x33939933;
-            mspos1 = 0x3966663;
-            break;
-        case 6:
-            mspos0 = 0x22a2aa22;
-            mspos1 = 0x2a65672;
-            break;
-        default:
-            debug_printf("r300: Bad number of multisamples!\n");
-        }
+     * to the AA state.
+     */
+    num_samples = r300->msaa_enable ? r300->num_samples : 1;
+
+    /* Sample positions. */
+    switch (num_samples) {
+    default:
+        mspos0 = r300_get_mspos(0, sample_locs_1x);
+        mspos1 = r300_get_mspos(1, sample_locs_1x);
+        break;
+    case 2:
+        mspos0 = r300_get_mspos(0, sample_locs_2x);
+        mspos1 = r300_get_mspos(1, sample_locs_2x);
+        break;
+    case 4:
+        mspos0 = r300_get_mspos(0, sample_locs_4x);
+        mspos1 = r300_get_mspos(1, sample_locs_4x);
+        break;
+    case 6:
+        mspos0 = r300_get_mspos(0, sample_locs_6x);
+        mspos1 = r300_get_mspos(1, sample_locs_6x);
+        break;
     }
 
     OUT_CS_REG_SEQ(R300_GB_MSPOS0, 2);
@@ -751,6 +831,18 @@ void r300_emit_rs_block_state(struct r300_context* r300,
     END_CS;
 }
 
+void r300_emit_sample_mask(struct r300_context *r300,
+                           unsigned size, void *state)
+{
+    unsigned mask = (*(unsigned*)state) & ((1 << 6)-1);
+    CS_LOCALS(r300);
+
+    BEGIN_CS(size);
+    OUT_CS_REG(R300_SC_SCREENDOOR,
+               mask | (mask << 6) | (mask << 12) | (mask << 18));
+    END_CS;
+}
+
 void r300_emit_scissor_state(struct r300_context* r300,
                              unsigned size, void* state)
 {
@@ -1176,6 +1268,7 @@ boolean r300_emit_buffer_validate(struct r300_context *r300,
 {
     struct pipe_framebuffer_state *fb =
         (struct pipe_framebuffer_state*)r300->fb_state.state;
+    struct r300_aa_state *aa = (struct r300_aa_state*)r300->aa_state.state;
     struct r300_textures_state *texstate =
         (struct r300_textures_state*)r300->textures_state.state;
     struct r300_resource *tex;
@@ -1201,6 +1294,14 @@ validate:
                                     r300_surface(fb->zsbuf)->domain);
         }
     }
+    /* The AA resolve buffer. */
+    if (r300->aa_state.dirty) {
+        if (aa->dest) {
+            r300->rws->cs_add_reloc(r300->cs, aa->dest->cs_buf,
+                                    RADEON_USAGE_WRITE,
+                                    aa->dest->domain);
+        }
+    }
     if (r300->textures_state.dirty) {
         /* ...textures... */
         for (i = 0; i < texstate->count; i++) {
@@ -1282,7 +1383,9 @@ unsigned r300_get_num_cs_end_dwords(struct r300_context *r300)
     dwords += 26; /* emit_query_end */
     dwords += r300->hyperz_state.size + 2; /* emit_hyperz_end + zcache flush */
     if (r300->screen->caps.is_r500)
-        dwords += 2;
+        dwords += 2; /* emit_index_bias */
+    if (r300->screen->info.drm_minor >= 6)
+        dwords += 3; /* MSPOS */
 
     return dwords;
 }