[Mesa-dev] [PATCH 4/9] i965: Stop allocating miptrees with first_level != 0.

[Eric Anholt]

If the caller shows up with GL_BASE_LEVEL != 0, it doesn't mean that the
texture will over the course of its lifetime have that nonzero baselevel,
it means that the caller is filling the texture from the bottom up for
some reason (one could imagine demand-loading detailed texture layers at
runtime, for example).  If we allocate from just the current baselevel, it
means when they come along with the next level up, we'll have to allocate
a new miptree and copy all of our bits out of the first miptree.
---
 src/mesa/drivers/dri/i965/intel_tex_image.c | 23 ++++++-----------------
 1 file changed, 6 insertions(+), 17 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_tex_image.c b/src/mesa/drivers/dri/i965/intel_tex_image.c
index 725d315..fe274bf 100644
--- a/src/mesa/drivers/dri/i965/intel_tex_image.c
+++ b/src/mesa/drivers/dri/i965/intel_tex_image.c
@@ -35,7 +35,6 @@ intel_miptree_create_for_teximage(struct brw_context *brw,
 				  struct intel_texture_image *intelImage,
 				  bool expect_accelerated_upload)
 {
-   GLuint firstLevel;
    GLuint lastLevel;
    int width, height, depth;
    GLuint i;
@@ -45,16 +44,8 @@ intel_miptree_create_for_teximage(struct brw_context *brw,
 
    DBG("%s\n", __FUNCTION__);
 
-   /* If this image disrespects BaseLevel, allocate from level zero.
-    * Usually BaseLevel == 0, so it's unlikely to happen.
-    */
-   if (intelImage->base.Base.Level < intelObj->base.BaseLevel)
-      firstLevel = 0;
-   else
-      firstLevel = intelObj->base.BaseLevel;
-
    /* Figure out image dimensions at start level. */
-   for (i = intelImage->base.Base.Level; i > firstLevel; i--) {
+   for (i = intelImage->base.Base.Level; i > 0; i--) {
       width <<= 1;
       if (height != 1)
          height <<= 1;
@@ -69,19 +60,17 @@ intel_miptree_create_for_teximage(struct brw_context *brw,
     */
    if ((intelObj->base.Sampler.MinFilter == GL_NEAREST ||
         intelObj->base.Sampler.MinFilter == GL_LINEAR) &&
-       intelImage->base.Base.Level == firstLevel &&
-       firstLevel == 0) {
-      lastLevel = firstLevel;
+       intelImage->base.Base.Level == 0) {
+      lastLevel = 0;
    } else {
-      lastLevel = (firstLevel +
-                   _mesa_get_tex_max_num_levels(intelObj->base.Target,
-                                                width, height, depth) - 1);
+      lastLevel = _mesa_get_tex_max_num_levels(intelObj->base.Target,
+                                               width, height, depth) - 1;
    }
 
    return intel_miptree_create(brw,
 			       intelObj->base.Target,
 			       intelImage->base.Base.TexFormat,
-			       firstLevel,
+			       0,
 			       lastLevel,
 			       width,
 			       height,
-- 
1.8.4.rc3