[Mesa-dev] [PATCH 1/3] i965/bdw: Fix setting the instancing state for the SGVS element

Neil Roberts neil at linux.intel.com
Mon Jul 13 10:01:13 PDT 2015

When gl_VertexID or gl_InstanceID is used a 3DSTATE_VF_SGVS
instruction is sent to create a sort of element to store the generated
values. The last instruction in this chunk of code looks like it was
trying to set the instancing state for the element using the
3DSTATE_VF_INSTANCING instruction. However it was sending
brw->vb.nr_buffers instead of the element index. This instruction is
supposed to take an element index and that is how it is used further
down in the function so the previous code looks wrong. Perhaps
previously the number of buffers coincidentally matched the number of
enabled elements so the value was generally correct anyway. In a
subsequent patch I want to change a bit how it chooses the SGVS
element index so this needs to be fixed.

Cc: "10.6 10.5" <mesa-stable at lists.freedesktop.org>
 src/mesa/drivers/dri/i965/gen8_draw_upload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/gen8_draw_upload.c b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
index 1af90ec..f7d9952 100644
--- a/src/mesa/drivers/dri/i965/gen8_draw_upload.c
+++ b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
@@ -74,7 +74,7 @@ gen8_emit_vertices(struct brw_context *brw)
       OUT_BATCH(_3DSTATE_VF_INSTANCING << 16 | (3 - 2));
-      OUT_BATCH(brw->vb.nr_buffers | GEN8_VF_INSTANCING_ENABLE);
    } else {

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