i915: Add support for HW rendering with no color draw buffer.

This is useful for shadow map generation.  Tested with glsl-bug-22603,
which rendered the depth textures with fallbacks before.

Acked-by: Chad Versace <chad@chad-versace.us>

diff --git a/src/mesa/drivers/dri/i915/i915_vtbl.c b/src/mesa/drivers/dri/i915/i915_vtbl.c
index bd0664bb79f267521843c766773ffb5dba70f418..495426aa6d869388ecd79b657dca7f064ecb4154 100644 (file)
--- a/src/mesa/drivers/dri/i915/i915_vtbl.c
+++ b/src/mesa/drivers/dri/i915/i915_vtbl.c
@@ -318,7 +318,8 @@ i915_emit_state(struct intel_context *intel)
 
    aper_array[aper_count++] = intel->batch.bo;
    if (dirty & I915_UPLOAD_BUFFERS) {
-      aper_array[aper_count++] = state->draw_region->buffer;
+      if (state->draw_region)
+        aper_array[aper_count++] = state->draw_region->buffer;
       if (state->depth_region)
         aper_array[aper_count++] = state->depth_region->buffer;
    }
@@ -388,23 +389,27 @@ i915_emit_state(struct intel_context *intel)
       if (INTEL_DEBUG & DEBUG_STATE)
          fprintf(stderr, "I915_UPLOAD_BUFFERS:\n");
 
-      count = 14;
+      count = 17;
       if (state->Buffer[I915_DESTREG_DRAWRECT0] != MI_NOOP)
          count++;
-      if (state->depth_region)
-         count += 3;
 
       BEGIN_BATCH(count);
       OUT_BATCH(state->Buffer[I915_DESTREG_CBUFADDR0]);
       OUT_BATCH(state->Buffer[I915_DESTREG_CBUFADDR1]);
-      OUT_RELOC(state->draw_region->buffer,
-               I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER, 0);
+      if (state->draw_region) {
+        OUT_RELOC(state->draw_region->buffer,
+                  I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER, 0);
+      } else {
+        OUT_BATCH(0);
+      }
 
+      OUT_BATCH(state->Buffer[I915_DESTREG_DBUFADDR0]);
+      OUT_BATCH(state->Buffer[I915_DESTREG_DBUFADDR1]);
       if (state->depth_region) {
-         OUT_BATCH(state->Buffer[I915_DESTREG_DBUFADDR0]);
-         OUT_BATCH(state->Buffer[I915_DESTREG_DBUFADDR1]);
          OUT_RELOC(state->depth_region->buffer,
                   I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER, 0);
+      } else {
+        OUT_BATCH(0);
       }
 
       OUT_BATCH(state->Buffer[I915_DESTREG_DV0]);
@@ -532,6 +537,12 @@ i915_set_buf_info_for_region(uint32_t *state, struct intel_region *region,
         if (region->tiling == I915_TILING_Y)
            state[1] |= BUF_3D_TILE_WALK_Y;
       }
+   } else {
+      /* Fill in a default pitch, since 0 is invalid.  We'll be
+       * setting the buffer offset to 0 and not referencing the
+       * buffer, so the pitch could really be any valid value.
+       */
+      state[1] |= BUF_3D_PITCH(4096);
    }
 }
 
@@ -596,6 +607,8 @@ i915_set_draw_region(struct intel_context *intel,
             LOD_PRECLAMP_OGL | TEX_DEFAULT_COLOR_OGL);
    if (irb != NULL) {
       value |= i915_render_target_format_for_mesa_format[irb->Base.Format];
+   } else {
+      value |= DV_PF_8888;
    }
 
    /* This isn't quite safe, thus being hidden behind an option.  When changing
@@ -670,6 +683,20 @@ i915_set_draw_region(struct intel_context *intel,
    I915_STATECHANGE(i915, I915_UPLOAD_BUFFERS);
 }
 
+static void
+i915_update_color_write_enable(struct i915_context *i915, bool enable)
+{
+   uint32_t dw = i915->state.Ctx[I915_CTXREG_LIS6];
+   if (enable)
+      dw |= S6_COLOR_WRITE_ENABLE;
+   else
+      dw &= ~S6_COLOR_WRITE_ENABLE;
+   if (dw != i915->state.Ctx[I915_CTXREG_LIS6]) {
+      I915_STATECHANGE(i915, I915_UPLOAD_CTX);
+      i915->state.Ctx[I915_CTXREG_LIS6] = dw;
+   }
+}
+
 /**
  * Update the hardware state for drawing into a window or framebuffer object.
  *
@@ -683,9 +710,10 @@ i915_set_draw_region(struct intel_context *intel,
 static void
 i915_update_draw_buffer(struct intel_context *intel)
 {
+   struct i915_context *i915 = (struct i915_context *)intel;
    struct gl_context *ctx = &intel->ctx;
    struct gl_framebuffer *fb = ctx->DrawBuffer;
-   struct intel_region *colorRegions[MAX_DRAW_BUFFERS], *depthRegion = NULL;
+   struct intel_region *colorRegion = NULL, *depthRegion = NULL;
    struct intel_renderbuffer *irbDepth = NULL, *irbStencil = NULL;
    bool fb_has_hiz = intel_framebuffer_has_hiz(fb);
 
@@ -717,49 +745,19 @@ i915_update_draw_buffer(struct intel_context *intel)
 
    /* How many color buffers are we drawing into?
     *
-    * If there are zero buffers or the buffer is too big, don't configure any
-    * regions for hardware drawing.  We'll fallback to software below.  Not
-    * having regions set makes some of the software fallback paths faster.
+    * If there is more than one drawbuffer (GL_FRONT_AND_BACK), or the
+    * drawbuffers are too big, we have to fallback to software.
     */
    if ((fb->Width > ctx->Const.MaxRenderbufferSize)
-       || (fb->Height > ctx->Const.MaxRenderbufferSize)
-       || (fb->_NumColorDrawBuffers == 0)) {
-      /* writing to 0  */
-      colorRegions[0] = NULL;
-   }
-   else if (fb->_NumColorDrawBuffers > 1) {
-       int i;
-       struct intel_renderbuffer *irb;
-
-       for (i = 0; i < fb->_NumColorDrawBuffers; i++) {
-           irb = intel_renderbuffer(fb->_ColorDrawBuffers[i]);
-           colorRegions[i] = irb ? irb->region : NULL;
-       }
-   }
-   else {
-      /* Get the intel_renderbuffer for the single colorbuffer we're drawing
-       * into.
-       */
-      if (fb->Name == 0) {
-        /* drawing to window system buffer */
-        if (fb->_ColorDrawBufferIndexes[0] == BUFFER_FRONT_LEFT)
-           colorRegions[0] = intel_get_rb_region(fb, BUFFER_FRONT_LEFT);
-        else
-           colorRegions[0] = intel_get_rb_region(fb, BUFFER_BACK_LEFT);
-      }
-      else {
-        /* drawing to user-created FBO */
-        struct intel_renderbuffer *irb;
-        irb = intel_renderbuffer(fb->_ColorDrawBuffers[0]);
-        colorRegions[0] = (irb && irb->region) ? irb->region : NULL;
-      }
-   }
-
-   if (!colorRegions[0]) {
-      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, GL_TRUE);
-   }
-   else {
-      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, GL_FALSE);
+       || (fb->Height > ctx->Const.MaxRenderbufferSize)) {
+      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, true);
+   } else if (fb->_NumColorDrawBuffers > 1) {
+      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, true);
+   } else {
+      struct intel_renderbuffer *irb;
+      irb = intel_renderbuffer(fb->_ColorDrawBuffers[0]);
+      colorRegion = irb ? irb->region : NULL;
+      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, false);
    }
 
    /* Check for depth fallback. */
@@ -801,7 +799,9 @@ i915_update_draw_buffer(struct intel_context *intel)
    ctx->Driver.Enable(ctx, GL_DEPTH_TEST, ctx->Depth.Test);
    ctx->Driver.Enable(ctx, GL_STENCIL_TEST, ctx->Stencil.Enabled);
 
-   intel->vtbl.set_draw_region(intel, colorRegions, depthRegion,
+   i915_update_color_write_enable(i915, colorRegion != NULL);
+
+   intel->vtbl.set_draw_region(intel, &colorRegion, depthRegion,
                                fb->_NumColorDrawBuffers);
    intel->NewGLState |= _NEW_BUFFERS;