Mesa (master): i965/gen6: Adjust render height in errata case for MSAA

[Jordan Justen]

Module: Mesa
Branch: master
Commit: 341995e4b59b569c48264a839a4fbac2f0ae43d1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=341995e4b59b569c48264a839a4fbac2f0ae43d1

Author: Jordan Justen <jordan.l.justen at intel.com>
Date:   Tue Feb 25 11:18:25 2014 -0800

i965/gen6: Adjust render height in errata case for MSAA

In the gen6 PRM Volume 1 Part 1: Graphics Core, Section
7.18.3.7.1 (Surface Arrays For all surfaces other than separate
stencil buffer):

 "[DevSNB] Errata: Sampler MSAA Qpitch will be 4 greater than the
  value calculated in the equation above , for every other odd Surface
  Height starting from 1 i.e. 1,5,9,13"

Since this Qpitch errata only impacts the sampler, we have to adjust
the input for the rendering surface to achieve the same qpitch. For
the affected heights, we increment the height by 1 for the rendering
surface.

Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
Acked-by: Chris Forbes <chrisf at ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/mesa/drivers/dri/i965/gen6_surface_state.c |   18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/gen6_surface_state.c b/src/mesa/drivers/dri/i965/gen6_surface_state.c
index 65bcf7d..27b4419 100644
--- a/src/mesa/drivers/dri/i965/gen6_surface_state.c
+++ b/src/mesa/drivers/dri/i965/gen6_surface_state.c
@@ -99,8 +99,24 @@ gen6_update_renderbuffer_surface(struct brw_context *brw,
    /* reloc */
    surf[1] = mt->bo->offset64;
 
+   /* In the gen6 PRM Volume 1 Part 1: Graphics Core, Section 7.18.3.7.1
+    * (Surface Arrays For all surfaces other than separate stencil buffer):
+    *
+    * "[DevSNB] Errata: Sampler MSAA Qpitch will be 4 greater than the value
+    *  calculated in the equation above , for every other odd Surface Height
+    *  starting from 1 i.e. 1,5,9,13"
+    *
+    * Since this Qpitch errata only impacts the sampler, we have to adjust the
+    * input for the rendering surface to achieve the same qpitch. For the
+    * affected heights, we increment the height by 1 for the rendering
+    * surface.
+    */
+   int height0 = irb->mt->logical_height0;
+   if (brw->gen == 6 && irb->mt->num_samples > 1 && (height0 % 4) == 1)
+      height0++;
+
    surf[2] = SET_FIELD(mt->logical_width0 - 1, BRW_SURFACE_WIDTH) |
-             SET_FIELD(mt->logical_height0 - 1, BRW_SURFACE_HEIGHT) |
+             SET_FIELD(height0 - 1, BRW_SURFACE_HEIGHT) |
              SET_FIELD(irb->mt_level - irb->mt->first_level, BRW_SURFACE_LOD);
 
    surf[3] = brw_get_surface_tiling_bits(mt->tiling) |