commit be5762dc1b25f991461bfe9bb520428eeb53a06b
Author: Nicholas Bishop <nbishop@neverware.com>
Date:   Thu Aug 25 01:08:43 2016 -0400

    Handle I915_SEMANTIC_POS when setting texCoords for gl_FragCoord
    
    Calling "src = draw_find_shader_output(i915->draw,
    TGSI_SEMANTIC_GENERIC, fs->generic_mapping[i]);" was returning -1,
    which later gets handled by pointing it at a buffer full of
    zeros. This caused gl_FragCoord to break.
    
    Change-Id: Ic04ac522f091eeb0d773e70bbc1e76d876259e1e

diff --git a/src/gallium/drivers/i915/i915_state_derived.c b/src/gallium/drivers/i915/i915_state_derived.c
index 177b854..dbfbc84 100644
--- a/src/gallium/drivers/i915/i915_state_derived.c
+++ b/src/gallium/drivers/i915/i915_state_derived.c
@@ -145,7 +145,12 @@ static void calculate_vertex_layout(struct i915_context *i915)
       uint hwtc;
       if (texCoords[i]) {
          hwtc = TEXCOORDFMT_4D;
-         src = draw_find_shader_output(i915->draw, TGSI_SEMANTIC_GENERIC, fs->generic_mapping[i]);
+         if (fs->generic_mapping[i] == I915_SEMANTIC_POS) {
+            src = draw_find_shader_output(i915->draw, TGSI_SEMANTIC_POSITION, 0);
+         }
+         else {
+            src = draw_find_shader_output(i915->draw, TGSI_SEMANTIC_GENERIC, fs->generic_mapping[i]);
+         }
          draw_emit_vertex_attr(&vinfo, EMIT_4F, src);
       }
       else {