drm/omap: cleanup OMAP_BO_SCANOUT use

omap_gem_new() has a comment about OMAP_BO_SCANOUT which does not make
sense. Also, for the TILER case, we drop OMAP_BO_SCANOUT flag for some
reason.

It's not clear what the original purpose of OMAP_BO_SCANOUT is, but
presuming it means "scanout buffer, something that can be consumed by
DSS", this patch cleans up the above issues.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191010120000.1421-7-jjhiblot@ti.com

drivers/gpu/drm/omapdrm/omap_gem.c

@@ -1155,7 +1155,6 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
 		 * Tiled buffers are always shmem paged backed. When they are
 		 * scanned out, they are remapped into DMM/TILER.
 		 */
-		flags &= ~OMAP_BO_SCANOUT;
 		flags |= OMAP_BO_MEM_SHMEM;
 
 		/*
@@ -1166,9 +1165,8 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
 		flags |= tiler_get_cpu_cache_flags();
 	} else if ((flags & OMAP_BO_SCANOUT) && !priv->has_dmm) {
 		/*
-		 * OMAP_BO_SCANOUT hints that the buffer doesn't need to be
-		 * tiled. However, to lower the pressure on memory allocation,
-		 * use contiguous memory only if no TILER is available.
+		 * If we don't have DMM, we must allocate scanout buffers
+		 * from contiguous DMA memory.
 		 */
 		flags |= OMAP_BO_MEM_DMA_API;
 	} else if (!(flags & OMAP_BO_MEM_DMABUF)) {