r600: allocate immed buffer resource for images.

In order to image readback we have to execute a MEM_RAT instruction
that needs a buffer to transfer the result into until the shader
can fetch it.

Tested-By: Gert Wollny <gw.fossdev@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/gallium/drivers/r600/r600_buffer_common.c

@@ -251,6 +251,7 @@ static void r600_buffer_destroy(struct pipe_screen *screen,
 
 	threaded_resource_deinit(buf);
 	util_range_destroy(&rbuffer->valid_buffer_range);
+	pipe_resource_reference((struct pipe_resource**)&rbuffer->immed_buffer, NULL);
 	pb_reference(&rbuffer->buf, NULL);
 	FREE(rbuffer);
 }
@@ -606,6 +607,7 @@ r600_alloc_buffer_struct(struct pipe_screen *screen,
 
 	rbuffer->buf = NULL;
 	rbuffer->bind_history = 0;
+	rbuffer->immed_buffer = NULL;
 	util_range_init(&rbuffer->valid_buffer_range);
 	return rbuffer;
 }

src/gallium/drivers/r600/r600_pipe_common.h

@@ -171,6 +171,12 @@ struct r600_resource {
 	/* Whether this resource is referenced by bindless handles. */
 	bool				texture_handle_allocated;
 	bool				image_handle_allocated;
+
+	/*
+	 * EG/Cayman only - for RAT operations hw need an immediate buffer
+	 * to store results in.
+	 */
+	struct r600_resource            *immed_buffer;
 };
 
 struct r600_transfer {
@@ -773,6 +779,9 @@ void evergreen_do_fast_color_clear(struct r600_common_context *rctx,
 				   const union pipe_color_union *color);
 void r600_init_screen_texture_functions(struct r600_common_screen *rscreen);
 void r600_init_context_texture_functions(struct r600_common_context *rctx);
+void eg_resource_alloc_immed(struct r600_common_screen *rscreen,
+			     struct r600_resource *res,
+			     unsigned immed_size);
 
 /* r600_viewport.c */
 void evergreen_apply_scissor_bug_workaround(struct r600_common_context *rctx,

src/gallium/drivers/r600/r600_texture.c

@@ -559,6 +559,7 @@ static void r600_texture_destroy(struct pipe_screen *screen,
 	struct r600_resource *resource = &rtex->resource;
 
 	r600_texture_reference(&rtex->flushed_depth_texture, NULL);
+	pipe_resource_reference((struct pipe_resource**)&resource->immed_buffer, NULL);
 
 	if (rtex->cmask_buffer != &rtex->resource) {
 	    r600_resource_reference(&rtex->cmask_buffer, NULL);
@@ -718,6 +719,15 @@ static void r600_texture_alloc_cmask_separate(struct r600_common_screen *rscreen
 	p_atomic_inc(&rscreen->compressed_colortex_counter);
 }
 
+void eg_resource_alloc_immed(struct r600_common_screen *rscreen,
+			     struct r600_resource *res,
+			     unsigned immed_size)
+{
+	res->immed_buffer = (struct r600_resource *)
+		pipe_buffer_create(&rscreen->b, PIPE_BIND_CUSTOM,
+				   PIPE_USAGE_DEFAULT, immed_size);
+}
+
 static void r600_texture_get_htile_size(struct r600_common_screen *rscreen,
 					struct r600_texture *rtex)
 {