From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [net-next PATCH RFC 19/26] arch/sparc: Add option to skip DMA sync as a part of map and unmap Date: Mon, 24 Oct 2016 14:27:30 -0400 (EDT) Message-ID: <20161024.142730.1316656811538193943.davem@davemloft.net> References: <20161024115737.16276.71059.stgit@ahduyck-blue-test.jf.intel.com> <20161024120607.16276.5989.stgit@ahduyck-blue-test.jf.intel.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, sparclinux@vger.kernel.org, brouer@redhat.com To: alexander.h.duyck@intel.com Return-path: 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 In-Reply-To: <20161024120607.16276.5989.stgit@ahduyck-blue-test.jf.intel.com> Sender: netdev-owner@vger.kernel.org List-ID: 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.