meta: use _mesa_prepare_mipmap_levels()

The prepare_mipmap_level() wrapper for _mesa_prepare_mipmap_level() is
not needed.  It only served to undo the GL_TEXTURE_1D_ARRAY height/depth
change was was made before the call to prepare_mipmap_level()

Said another way, regardless of how the meta code manipulates the height/
depth dims for GL_TEXTURE_1D_ARRAY, the gl_texture_image dimensions are
correctly set up by _mesa_prepare_mipmap_levels().

Tested by plugging _mesa_meta_GenerateMipmap() into the swrast driver
and testing with piglit.

v2 (idr): Early out of the mipmap generation loop with dstImage is NULL.
This can occur for immutable textures that have a limited range of
levels or in the presense of memory allocation failures.  Fixes
arb_texture_view-mipgen on Intel platforms.

Reviewed-by: José Fonseca <jfonseca@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Tested-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/drivers/common/meta_generate_mipmap.c

@@ -137,21 +137,6 @@ _mesa_meta_glsl_generate_mipmap_cleanup(struct gl_context *ctx,
    _mesa_meta_blit_shader_table_cleanup(ctx, &mipmap->shaders);
 }
 
-static GLboolean
-prepare_mipmap_level(struct gl_context *ctx,
-                     struct gl_texture_object *texObj, GLuint level,
-                     GLsizei width, GLsizei height, GLsizei depth,
-                     GLenum intFormat, mesa_format format)
-{
-   if (texObj->Target == GL_TEXTURE_1D_ARRAY) {
-      /* Work around Mesa expecting the number of array slices in "height". */
-      height = depth;
-      depth = 1;
-   }
-
-   return _mesa_prepare_mipmap_level(ctx, texObj, level, width, height, depth,
-                                     0, intFormat, format);
-}
 
 /**
  * Called via ctx->Driver.GenerateMipmap()
@@ -270,6 +255,8 @@ _mesa_meta_GenerateMipmap(struct gl_context *ctx, GLenum target,
    /* texture is already locked, unlock now */
    _mesa_unlock_texture(ctx, texObj);
 
+   _mesa_prepare_mipmap_levels(ctx, texObj, baseLevel, maxLevel);
+
    for (dstLevel = baseLevel + 1; dstLevel <= maxLevel; dstLevel++) {
       const struct gl_texture_image *srcImage;
       struct gl_texture_image *dstImage;
@@ -309,17 +296,14 @@ _mesa_meta_GenerateMipmap(struct gl_context *ctx, GLenum target,
       _mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL,
                                 (GLint *) &dstLevel, false);
 
-      if (!prepare_mipmap_level(ctx, texObj, dstLevel,
-                                dstWidth, dstHeight, dstDepth,
-                                srcImage->InternalFormat,
-                                srcImage->TexFormat)) {
-         /* All done.  We either ran out of memory or we would go beyond the
-          * last valid level of an immutable texture if we continued.
-          */
-         break;
-      }
       dstImage = _mesa_select_tex_image(texObj, faceTarget, dstLevel);
 
+      /* All done.  We either ran out of memory or we would go beyond the last
+       * valid level of an immutable texture if we continued.
+       */
+      if (dstImage == NULL)
+         break;
+
       /* limit minification to src level */
       _mesa_texture_parameteriv(ctx, texObj, GL_TEXTURE_MAX_LEVEL,
                                 (GLint *) &srcLevel, false);