[Mesa-dev] [PATCH v3 04/16] i965/draw: Delay when we get the bo for vertex buffers

[Jason Ekstrand]

The previous code got the BO the first time we encountered it.  However,
this can potentially lead to problems if the BO is used for multiple arrays
with the same buffer object because the range we declare as busy may not be
quite right.  By delaying the call to intel_bufferobj_buffer, we can ensure
that we have the full range for the given buffer.

Cc: "11.1 11.2" <mesa-stable at lists.freedesktop.org>
Reviewed-by: Iago Toral Quiroga <itoral at igalia.com>
---
 src/mesa/drivers/dri/i965/brw_draw_upload.c | 71 ++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 22 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_draw_upload.c b/src/mesa/drivers/dri/i965/brw_draw_upload.c
index 3ec37f8..0a7725d 100644
--- a/src/mesa/drivers/dri/i965/brw_draw_upload.c
+++ b/src/mesa/drivers/dri/i965/brw_draw_upload.c
@@ -453,6 +453,11 @@ brw_prepare_vertices(struct brw_context *brw)
    if (brw->vb.nr_buffers)
       return;
 
+   /* The range of data in a given buffer represented as [min, max) */
+   struct intel_buffer_object *enabled_buffer[VERT_ATTRIB_MAX];
+   uint32_t buffer_range_start[VERT_ATTRIB_MAX];
+   uint32_t buffer_range_end[VERT_ATTRIB_MAX];
+
    for (i = j = 0; i < brw->vb.nr_enabled; i++) {
       struct brw_vertex_element *input = brw->vb.enabled[i];
       const struct gl_client_array *glarray = input->glarray;
@@ -460,12 +465,31 @@ brw_prepare_vertices(struct brw_context *brw)
       if (_mesa_is_bufferobj(glarray->BufferObj)) {
 	 struct intel_buffer_object *intel_buffer =
 	    intel_buffer_object(glarray->BufferObj);
-	 unsigned k;
+
+         const uint32_t offset = (uintptr_t)glarray->Ptr;
+
+         uint32_t start, range;
+         if (glarray->InstanceDivisor) {
+            start = offset;
+            range = (glarray->StrideB * ((brw->num_instances /
+                                         glarray->InstanceDivisor) - 1) +
+                     glarray->_ElementSize);
+         } else {
+            if (!brw->vb.index_bounds_valid) {
+               start = 0;
+               range = intel_buffer->Base.Size;
+            } else {
+               start = offset + min_index * glarray->StrideB;
+               range = (glarray->StrideB * (max_index - min_index) +
+                        glarray->_ElementSize);
+            }
+         }
 
 	 /* If we have a VB set to be uploaded for this buffer object
 	  * already, reuse that VB state so that we emit fewer
 	  * relocations.
 	  */
+	 unsigned k;
 	 for (k = 0; k < i; k++) {
 	    const struct gl_client_array *other = brw->vb.enabled[k]->glarray;
 	    if (glarray->BufferObj == other->BufferObj &&
@@ -475,6 +499,9 @@ brw_prepare_vertices(struct brw_context *brw)
 	    {
 	       input->buffer = brw->vb.enabled[k]->buffer;
 	       input->offset = glarray->Ptr - other->Ptr;
+
+               buffer_range_start[k] = MIN2(buffer_range_start[k], start);
+               buffer_range_end[k] = MAX2(buffer_range_end[k], start + range);
 	       break;
 	    }
 	 }
@@ -482,29 +509,13 @@ brw_prepare_vertices(struct brw_context *brw)
 	    struct brw_vertex_buffer *buffer = &brw->vb.buffers[j];
 
 	    /* Named buffer object: Just reference its contents directly. */
-	    buffer->offset = (uintptr_t)glarray->Ptr;
+	    buffer->offset = offset;
 	    buffer->stride = glarray->StrideB;
 	    buffer->step_rate = glarray->InstanceDivisor;
 
-            uint32_t offset, size;
-            if (glarray->InstanceDivisor) {
-               offset = buffer->offset;
-               size = (buffer->stride * ((brw->num_instances /
-                                          glarray->InstanceDivisor) - 1) +
-                       glarray->_ElementSize);
-            } else {
-               if (!brw->vb.index_bounds_valid) {
-                  offset = 0;
-                  size = intel_buffer->Base.Size;
-               } else {
-                  offset = buffer->offset + min_index * buffer->stride;
-                  size = (buffer->stride * (max_index - min_index) +
-                          glarray->_ElementSize);
-               }
-            }
-            buffer->bo = intel_bufferobj_buffer(brw, intel_buffer,
-                                                offset, size);
-            drm_intel_bo_reference(buffer->bo);
+            enabled_buffer[j] = intel_buffer;
+            buffer_range_start[j] = start;
+            buffer_range_end[j] = start + range;
 
 	    input->buffer = j++;
 	    input->offset = 0;
@@ -519,7 +530,7 @@ brw_prepare_vertices(struct brw_context *brw)
 	  * probably a service to the poor programmer to do so rather than
 	  * trying to just not render.
 	  */
-	 assert(input->offset < brw->vb.buffers[input->buffer].bo->size);
+	 assert(input->offset < intel_buffer->Base.Size);
       } else {
 	 /* Queue the buffer object up to be uploaded in the next pass,
 	  * when we've decided if we're doing interleaved or not.
@@ -554,6 +565,22 @@ brw_prepare_vertices(struct brw_context *brw)
       }
    }
 
+   /* Now that we've set up all of the buffers, we walk through and reference
+    * each of them.  We do this late so that we get the right size in each
+    * buffer and don't reference too little data.
+    */
+   for (i = 0; i < j; i++) {
+      struct brw_vertex_buffer *buffer = &brw->vb.buffers[i];
+      if (buffer->bo)
+         continue;
+
+      const uint32_t start = buffer_range_start[i];
+      const uint32_t range = buffer_range_end[i] - buffer_range_start[i];
+
+      buffer->bo = intel_bufferobj_buffer(brw, enabled_buffer[i], start, range);
+      drm_intel_bo_reference(buffer->bo);
+   }
+
    /* If we need to upload all the arrays, then we can trim those arrays to
     * only the used elements [min_index, max_index] so long as we adjust all
     * the values used in the 3DPRIMITIVE i.e. by setting the vertex bias.
-- 
2.5.0.400.gff86faf