[Mesa-dev] [PATCH 3/4] i965/gen7: Fix up the transform feedback buffer pointers on later batches.

[Eric Anholt]

Fixes piglit EXT_transform_feedback/intervening-read
---
 src/mesa/drivers/dri/i965/brw_context.h    |    1 +
 src/mesa/drivers/dri/i965/brw_vtbl.c       |    6 ++++++
 src/mesa/drivers/dri/i965/gen6_sol.c       |    1 +
 src/mesa/drivers/dri/i965/gen7_sol_state.c |   13 ++++++++++---
 4 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index 873e172..9f9b113 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -988,6 +988,7 @@ struct brw_context
    struct brw_sol_state {
       uint32_t svbi_0_starting_index;
       uint32_t svbi_0_max_index;
+      uint32_t offset_0_batch_start;
       uint32_t primitives_generated;
       uint32_t primitives_written;
    } sol;
diff --git a/src/mesa/drivers/dri/i965/brw_vtbl.c b/src/mesa/drivers/dri/i965/brw_vtbl.c
index d348806..be975d1 100644
--- a/src/mesa/drivers/dri/i965/brw_vtbl.c
+++ b/src/mesa/drivers/dri/i965/brw_vtbl.c
@@ -177,6 +177,12 @@ static void brw_new_batch( struct intel_context *intel )
 
    brw->state_batch_count = 0;
 
+   /* Gen7 needs to track what the real transform feedback vertex count was at
+    * the start of the batch, since the kernel will be resetting the offset to
+    * 0.
+    */
+   brw->sol.offset_0_batch_start = brw->sol.svbi_0_starting_index;
+
    brw->vb.nr_current_buffers = 0;
    brw->ib.type = -1;
 
diff --git a/src/mesa/drivers/dri/i965/gen6_sol.c b/src/mesa/drivers/dri/i965/gen6_sol.c
index f724802..41923b7 100644
--- a/src/mesa/drivers/dri/i965/gen6_sol.c
+++ b/src/mesa/drivers/dri/i965/gen6_sol.c
@@ -132,6 +132,7 @@ brw_begin_transform_feedback(struct gl_context *ctx, GLenum mode,
    brw->state.dirty.brw |= BRW_NEW_SOL_INDICES;
    brw->sol.svbi_0_starting_index = 0;
    brw->sol.svbi_0_max_index = max_index;
+   brw->sol.offset_0_batch_start = 0;
 }
 
 void
diff --git a/src/mesa/drivers/dri/i965/gen7_sol_state.c b/src/mesa/drivers/dri/i965/gen7_sol_state.c
index ba9fb67..eb52930 100644
--- a/src/mesa/drivers/dri/i965/gen7_sol_state.c
+++ b/src/mesa/drivers/dri/i965/gen7_sol_state.c
@@ -56,6 +56,7 @@ upload_3dstate_so_buffers(struct brw_context *brw)
       struct gl_buffer_object *bufferobj = xfb_obj->Buffers[i];
       drm_intel_bo *bo;
       uint32_t start, end;
+      uint32_t stride;
 
       if (!xfb_obj->Buffers[i]) {
 	 /* The pitch of 0 in this command indicates that the buffer is
@@ -72,17 +73,23 @@ upload_3dstate_so_buffers(struct brw_context *brw)
       }
 
       bo = intel_buffer_object(bufferobj)->buffer;
+      stride = linked_xfb_info->BufferStride[i] * 4;
 
       start = xfb_obj->Offset[i];
       assert(start % 4 == 0);
       end = ALIGN(start + xfb_obj->Size[i], 4);
       assert(end <= bo->size);
 
+      /* Offset the starting offset by the current vertex index into the
+       * feedback buffer, offset register is always set to 0 at the start of the
+       * batchbuffer.
+       */
+      start += brw->sol.offset_0_batch_start * stride;
+      assert(start <= end);
+
       BEGIN_BATCH(4);
       OUT_BATCH(_3DSTATE_SO_BUFFER << 16 | (4 - 2));
-      OUT_BATCH((i << SO_BUFFER_INDEX_SHIFT) |
-		((linked_xfb_info->BufferStride[i] * 4) <<
-		 SO_BUFFER_PITCH_SHIFT));
+      OUT_BATCH((i << SO_BUFFER_INDEX_SHIFT) | stride);
       OUT_RELOC(bo, I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER, start);
       OUT_RELOC(bo, I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER, end);
       ADVANCE_BATCH();
-- 
1.7.7.3