gallium: Add texture usage flags, special-case allocation of display targets

For many envirionments it's necessary to allocate display targets
in a window-system friendly manner.  Add facilities so that a driver
can tell if a texture is likely to be used to generate a display surface
and if use special allocation paths if necessary.

Hook up softpipe to call into the winsys->surface_alloc_storage()
routine in this case, though we probably want to change that interface
slightly also.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/mesa/state_tracker/st_cb_bitmap.c b/src/mesa/state_tracker/st_cb_bitmap.c
index 873b765c2c2..f816e591042 100644
--- a/src/mesa/state_tracker/st_cb_bitmap.c
+++ b/src/mesa/state_tracker/st_cb_bitmap.c
@@ -321,7 +321,8 @@ make_bitmap_texture(GLcontext *ctx, GLsizei width, GLsizei height,
     * Create texture to hold bitmap pattern.
     */
    pt = st_texture_create(ctx->st, PIPE_TEXTURE_2D, ctx->st->bitmap.tex_format,
-                          0, width, height, 1, 0);
+                          0, width, height, 1, 0,
+                          PIPE_TEXTURE_USAGE_SAMPLER);
    if (!pt) {
       _mesa_unmap_bitmap_pbo(ctx, unpack);
       return NULL;
@@ -539,7 +540,8 @@ reset_cache(struct st_context *st)
    cache->texture = st_texture_create(st, PIPE_TEXTURE_2D,
                                       st->bitmap.tex_format, 0,
                                       BITMAP_CACHE_WIDTH, BITMAP_CACHE_HEIGHT,
-                                      1, 0);
+                                      1, 0,
+                                      PIPE_TEXTURE_USAGE_SAMPLER);
 
    /* Map the texture surface.
     * Subsequent glBitmap calls will write into the texture image.