1 files changed, 46 insertions, 18 deletions

diff --git a/src/gallium/winsys/g3dvl/nouveau/nouveau_winsys_pipe.c b/src/gallium/winsys/g3dvl/nouveau/nouveau_winsys_pipe.c
index d841eb4a04..17c409e1ce 100644
--- a/src/gallium/winsys/g3dvl/nouveau/nouveau_winsys_pipe.c
+++ b/src/gallium/winsys/g3dvl/nouveau/nouveau_winsys_pipe.c
@@ -89,25 +89,10 @@ nouveau_surface_release(struct pipe_winsys *ws, struct pipe_surface **s)
 	}
 }
 
-static struct pipe_buffer *
-nouveau_pipe_bo_create(struct pipe_winsys *pws, unsigned alignment,
-		       unsigned usage, unsigned size)
+static uint32_t
+nouveau_flags_from_usage(struct nouveau_context *nv, unsigned usage)
 {
-	struct nouveau_pipe_winsys *nvpws = (struct nouveau_pipe_winsys *)pws;
-	struct nouveau_context *nv = nvpws->nv;
-	struct nouveau_device *dev = nv->nv_screen->device;
-	struct nouveau_pipe_buffer *nvbuf;
-	uint32_t flags;
-
-	nvbuf = calloc(1, sizeof(*nvbuf));
-	if (!nvbuf)
-		return NULL;
-	nvbuf->base.refcount = 1;
-	nvbuf->base.alignment = alignment;
-	nvbuf->base.usage = usage;
-	nvbuf->base.size = size;
-
-	flags = NOUVEAU_BO_LOCAL;
+	uint32_t flags = NOUVEAU_BO_LOCAL;
 
 	if (usage & PIPE_BUFFER_USAGE_PIXEL) {
 		if (usage & NOUVEAU_BUFFER_USAGE_TEXTURE)
@@ -126,6 +111,29 @@ nouveau_pipe_bo_create(struct pipe_winsys *pws, unsigned alignment,
 			flags |= NOUVEAU_BO_GART;
 	}
 
+	return flags;
+}
+
+static struct pipe_buffer *
+nouveau_pipe_bo_create(struct pipe_winsys *pws, unsigned alignment,
+		       unsigned usage, unsigned size)
+{
+	struct nouveau_pipe_winsys *nvpws = (struct nouveau_pipe_winsys *)pws;
+	struct nouveau_context *nv = nvpws->nv;
+	struct nouveau_device *dev = nv->nv_screen->device;
+	struct nouveau_pipe_buffer *nvbuf;
+	uint32_t flags;
+
+	nvbuf = calloc(1, sizeof(*nvbuf));
+	if (!nvbuf)
+		return NULL;
+	nvbuf->base.refcount = 1;
+	nvbuf->base.alignment = alignment;
+	nvbuf->base.usage = usage;
+	nvbuf->base.size = size;
+
+	flags = nouveau_flags_from_usage(nv, usage);
+
 	if (nouveau_bo_new(dev, flags, alignment, size, &nvbuf->bo)) {
 		free(nvbuf);
 		return NULL;
@@ -176,6 +184,26 @@ nouveau_pipe_bo_map(struct pipe_winsys *pws, struct pipe_buffer *buf,
 	if (flags & PIPE_BUFFER_USAGE_CPU_WRITE)
 		map_flags |= NOUVEAU_BO_WR;
 
+	if ((map_flags & NOUVEAU_BO_RDWR) == NOUVEAU_BO_WR &&
+	    !nouveau_bo_busy(nvbuf->bo, map_flags)) {
+		/* XXX: Technically incorrect. If the client maps a buffer for write-only
+		 * and leaves part of the buffer untouched it probably expects those parts
+		 * to remain intact. This is violated because we allocate a whole new buffer
+		 * and don't copy the previous buffer's contents, so this optimization is
+		 * only valid if the client intends to overwrite the whole buffer.
+		 */
+		struct nouveau_pipe_winsys *nvpws = (struct nouveau_pipe_winsys *)pws;
+		struct nouveau_context *nv = nvpws->nv;
+		struct nouveau_device *dev = nv->nv_screen->device;
+		struct nouveau_bo *rename;
+		uint32_t flags = nouveau_flags_from_usage(nv, buf->usage);
+
+		if (!nouveau_bo_new(dev, flags, buf->alignment, buf->size, &rename)) {
+			nouveau_bo_del(&nvbuf->bo);
+			nvbuf->bo = rename;
+		}
+	}
+
 	if (nouveau_bo_map(nvbuf->bo, map_flags))
 		return NULL;
 	return nvbuf->bo->map;