i915_gem_object_prepare_write
err = i915_gem_object_prepare_write(obj, &flushes);
int i915_gem_object_prepare_write(struct drm_i915_gem_object *obj,
err = i915_gem_object_prepare_write(ctx->obj, &needs_clflush);
err = i915_gem_object_prepare_write(obj, &need_flush);
ret = i915_gem_object_prepare_write(dst_obj, &dst_needs_clflush);
ret = i915_gem_object_prepare_write(obj, &needs_clflush);