i965: Quote the PRM on a HorzStride subtlety

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>

diff --git a/src/mesa/drivers/dri/i965/brw_eu_emit.c b/src/mesa/drivers/dri/i965/brw_eu_emit.c
index fecbff1..b34754a 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_eu_emit.c
+++ b/src/mesa/drivers/dri/i965/brw_eu_emit.c
@@ -126,7 +126,10 @@ brw_set_dest(struct brw_compile *p, struct brw_instruction *insn,
       else {
         insn->bits1.da16.dest_subreg_nr = dest.subnr / 16;
         insn->bits1.da16.dest_writemask = dest.dw1.bits.writemask;
-        /* even ignored in da16, still need to set as '01' */
+        /* From the Ivybridge PRM, Vol 4, Part 3, Section 5.2.4.1:
+         *    Although Dst.HorzStride is a don't care for Align16, HW needs
+         *    this to be programmed as "01".
+         */
         insn->bits1.da16.dest_horiz_stride = 1;
       }
    }