[Mesa-dev] [PATCH] i965: setup address rounding enable bits

[Yuanhan Liu]

The patch(based on the reading of the emulator) came from while I was
trying to fix the oglc pbo texImage.1PBODefaults fail. This case
generates a texture with the width and height equal to window's width
and height respectively, then try to texture it on the whole window.
So, it's exactly one texel for one pixel.  And, the min filter and mag
filter are GL_LINEAR. It runs with swrast OK, as expected. But it failed
with i965 driver.

Well, you can't tell the difference from the screen, as the error is
quite tiny. From my digging, it seems that there are some tiny error
happened while getting tex address. This will break the one texel for
one pixel rule in this case. Thus the linear result is taken, with tiny
error.

This patch would fix all oglc pbo subcase fail with the same issue on
both ILK, SNB and IVB.

v2: comments from Ian, make the address_round filed assignment consistent.
    (the sampler is alread memset to 0 by the xxx_update_samper_state
     caller, so need to assign 0 first)

Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
---
 src/mesa/drivers/dri/i965/brw_defines.h          |    7 +++++++
 src/mesa/drivers/dri/i965/brw_wm_sampler_state.c |    9 +++++++++
 src/mesa/drivers/dri/i965/gen7_sampler_state.c   |    9 +++++++++
 3 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index a111630..e4647ff 100644
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -196,6 +196,13 @@
 #define BRW_MIPFILTER_NEAREST     1   
 #define BRW_MIPFILTER_LINEAR      3
 
+#define BRW_ADDRESS_ROUNDING_ENABLE_U_MAG	0x20
+#define BRW_ADDRESS_ROUNDING_ENABLE_U_MIN	0x10
+#define BRW_ADDRESS_ROUNDING_ENABLE_V_MAG	0x08
+#define BRW_ADDRESS_ROUNDING_ENABLE_V_MIN	0x04
+#define BRW_ADDRESS_ROUNDING_ENABLE_R_MAG	0x02
+#define BRW_ADDRESS_ROUNDING_ENABLE_R_MIN	0x01
+
 #define BRW_POLYGON_FRONT_FACING     0
 #define BRW_POLYGON_BACK_FACING      1
 
diff --git a/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c b/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c
index 6834eba..8938561 100644
--- a/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c
+++ b/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c
@@ -312,6 +312,15 @@ static void brw_update_sampler_state(struct brw_context *brw,
 			      intel->batch.bo, brw->wm.sdc_offset[unit],
 			      I915_GEM_DOMAIN_SAMPLER, 0);
    }
+
+   if (sampler->ss0.min_filter != BRW_MAPFILTER_NEAREST)
+      sampler->ss3.address_round |= BRW_ADDRESS_ROUNDING_ENABLE_U_MIN |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_V_MIN |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_R_MIN;
+   if (sampler->ss0.mag_filter != BRW_MAPFILTER_NEAREST)
+      sampler->ss3.address_round |= BRW_ADDRESS_ROUNDING_ENABLE_U_MAG |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_V_MAG |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_R_MAG;
 }
 
 
diff --git a/src/mesa/drivers/dri/i965/gen7_sampler_state.c b/src/mesa/drivers/dri/i965/gen7_sampler_state.c
index aee67c8..f6f51c5 100644
--- a/src/mesa/drivers/dri/i965/gen7_sampler_state.c
+++ b/src/mesa/drivers/dri/i965/gen7_sampler_state.c
@@ -167,6 +167,15 @@ gen7_update_sampler_state(struct brw_context *brw, int unit,
    upload_default_color(brw, gl_sampler, unit);
 
    sampler->ss2.default_color_pointer = brw->wm.sdc_offset[unit] >> 5;
+
+   if (sampler->ss0.min_filter != BRW_MAPFILTER_NEAREST)
+      sampler->ss3.address_round |= BRW_ADDRESS_ROUNDING_ENABLE_U_MIN |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_V_MIN |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_R_MIN;
+   if (sampler->ss0.mag_filter != BRW_MAPFILTER_NEAREST)
+      sampler->ss3.address_round |= BRW_ADDRESS_ROUNDING_ENABLE_U_MAG |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_V_MAG |
+                                    BRW_ADDRESS_ROUNDING_ENABLE_R_MAG;
 }
 
 
-- 
1.7.4.4