From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759830AbbIDPcM (ORCPT ); Fri, 4 Sep 2015 11:32:12 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:36435 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759227AbbIDPcJ (ORCPT ); Fri, 4 Sep 2015 11:32:09 -0400 Date: Fri, 4 Sep 2015 17:32:05 +0200 From: Richard Cochran To: Thomas Gleixner Cc: "Hall, Christopher S" , "Kirsher, Jeffrey T" , "hpa@zytor.com" , "mingo@redhat.com" , "john.stultz@linaro.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "intel-wired-lan@lists.osuosl.org" , "peterz@infradead.org" Subject: Re: [PATCH v3 1/4] Add correlated clocksource deriving system time from an auxiliary clocksource Message-ID: <20150904153205.GA17151@localhost.localdomain> References: <1440183128-1384-1-git-send-email-christopher.s.hall@intel.com> <1440183128-1384-2-git-send-email-christopher.s.hall@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 04, 2015 at 03:02:19PM +0200, Thomas Gleixner wrote: > No. This function is explicitely for the precise timestamp usecase, > which is required by PTP and other sane use cases. Right. The audio department only needs to know the (ART, ptp) offset. The kernel and user space never need the (ART, mediaclock) offset. That is private information for the DSP. As long as user space reads (ART, ptp) and provides this regulary to the audio DSP, then the DSP will have all the information it needs to figure out (ptp, mediaclock). Thanks, Richard