Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964958AbcJXS1e (ORCPT ); Mon, 24 Oct 2016 14:27:34 -0400 Received: from shards.monkeyblade.net ([184.105.139.130]:38674 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932470AbcJXS1c (ORCPT ); Mon, 24 Oct 2016 14:27:32 -0400 Date: Mon, 24 Oct 2016 14:27:30 -0400 (EDT) Message-Id: <20161024.142730.1316656811538193943.davem@davemloft.net> To: alexander.h.duyck@intel.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, sparclinux@vger.kernel.org, brouer@redhat.com Subject: Re: [net-next PATCH RFC 19/26] arch/sparc: Add option to skip DMA sync as a part of map and unmap From: David Miller In-Reply-To: <20161024120607.16276.5989.stgit@ahduyck-blue-test.jf.intel.com> References: <20161024115737.16276.71059.stgit@ahduyck-blue-test.jf.intel.com> <20161024120607.16276.5989.stgit@ahduyck-blue-test.jf.intel.com> X-Mailer: Mew version 6.7 on Emacs 24.5 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Mon, 24 Oct 2016 11:27:31 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 580 Lines: 14 From: Alexander Duyck Date: Mon, 24 Oct 2016 08:06:07 -0400 > This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to > avoid invoking cache line invalidation if the driver will just handle it > via a sync_for_cpu or sync_for_device call. > > Cc: "David S. Miller" > Cc: sparclinux@vger.kernel.org > Signed-off-by: Alexander Duyck This is fine for avoiding the flush for performance reasons, but the chip isn't going to write anything back unless the device wrote into the area.