i915: Clamp minimum lod to maximum texture level too.

Otherwise, we'd run into minlod > maxlod, and the sampler would give
us the undefined we asked for.

Bug #24846.  Fixes OGLC texlod.c.

diff --git a/src/mesa/drivers/dri/i915/i915_texstate.c b/src/mesa/drivers/dri/i915/i915_texstate.c
index ff9ab88c5abe9d90aa13823fcc7a9badc4fdcd36..9c56b55feebc3bf03f5c7753702c065ed4a8dfc9 100644 (file)
--- a/src/mesa/drivers/dri/i915/i915_texstate.c
+++ b/src/mesa/drivers/dri/i915/i915_texstate.c
@@ -281,6 +281,7 @@ i915_update_tex_unit(struct intel_context *intel, GLuint unit, GLuint ss3)
       GLenum ws = tObj->WrapS;
       GLenum wt = tObj->WrapT;
       GLenum wr = tObj->WrapR;
+      float minlod;
 
       /* We program 1D textures as 2D textures, so the 2D texcoord could
        * result in sampling border values if we don't set the T wrap to
@@ -321,8 +322,9 @@ i915_update_tex_unit(struct intel_context *intel, GLuint unit, GLuint ss3)
           (translate_wrap_mode(wt) << SS3_TCY_ADDR_MODE_SHIFT) |
           (translate_wrap_mode(wr) << SS3_TCZ_ADDR_MODE_SHIFT));
 
+      minlod = MIN2(tObj->MinLod, tObj->_MaxLevel - tObj->BaseLevel);
       state[I915_TEXREG_SS3] |= (unit << SS3_TEXTUREMAP_INDEX_SHIFT);
-      state[I915_TEXREG_SS3] |= (U_FIXED(CLAMP(tObj->MinLod, 0.0, 11.0), 4) <<
+      state[I915_TEXREG_SS3] |= (U_FIXED(CLAMP(minlod, 0.0, 11.0), 4) <<
                                 SS3_MIN_LOD_SHIFT);
 
    }