gallium: comment/document usage flags

diff --git a/src/gallium/include/pipe/p_screen.h b/src/gallium/include/pipe/p_screen.h
index 48625bf31278dc33c488e701c6cba34dc8d97e50..e4a92228093b84774d5fa0d25bb1a62e87951d1e 100644 (file)
--- a/src/gallium/include/pipe/p_screen.h
+++ b/src/gallium/include/pipe/p_screen.h
@@ -121,7 +121,9 @@ struct pipe_screen {
 
    void (*texture_destroy)(struct pipe_texture *pt);
 
-   /** Get a surface which is a "view" into a texture */
+   /** Get a 2D surface which is a "view" into a texture
+    * \param usage  bitmaks of PIPE_BUFFER_USAGE_* read/write flags
+    */
    struct pipe_surface *(*get_tex_surface)(struct pipe_screen *,
                                            struct pipe_texture *texture,
                                            unsigned face, unsigned level,