zink: use IMMUTABLE for dummy xfb buffer

this is never getting read back or anything so don't waste BAR allocation

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13849>

diff --git a/src/gallium/drivers/zink/zink_context.c b/src/gallium/drivers/zink/zink_context.c
index defca8d..29c56dc 100644 (file)
--- a/src/gallium/drivers/zink/zink_context.c
+++ b/src/gallium/drivers/zink/zink_context.c
@@ -4182,7 +4182,7 @@ zink_context_create(struct pipe_screen *pscreen, void *priv, unsigned flags)
    if (!ctx->dummy_vertex_buffer)
       goto fail;
    ctx->dummy_xfb_buffer = pipe_buffer_create(&screen->base,
-      PIPE_BIND_STREAM_OUTPUT, PIPE_USAGE_DEFAULT, sizeof(data));
+      PIPE_BIND_STREAM_OUTPUT, PIPE_USAGE_IMMUTABLE, sizeof(data));
    if (!ctx->dummy_xfb_buffer)
       goto fail;
    for (unsigned i = 0; i < ARRAY_SIZE(ctx->dummy_surface); i++) {