Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932130AbbG1DoJ (ORCPT ); Mon, 27 Jul 2015 23:44:09 -0400 Received: from mail-ig0-f175.google.com ([209.85.213.175]:37137 "EHLO mail-ig0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755125AbbG1DoH (ORCPT ); Mon, 27 Jul 2015 23:44:07 -0400 MIME-Version: 1.0 In-Reply-To: <1438044416-15588-2-git-send-email-christopher.s.hall@intel.com> References: <1438044416-15588-1-git-send-email-christopher.s.hall@intel.com> <1438044416-15588-2-git-send-email-christopher.s.hall@intel.com> Date: Mon, 27 Jul 2015 20:44:06 -0700 Message-ID: Subject: Re: [PATCH 1/5] Add functions producing system time given a backing counter value From: John Stultz To: Christopher Hall Cc: Thomas Gleixner , Richard Cochran , Ingo Molnar , Jeff Kirsher , john.ronciak@intel.com, "H. Peter Anvin" , "x86@kernel.org" , lkml , netdev@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1088 Lines: 27 On Mon, Jul 27, 2015 at 5:46 PM, Christopher Hall wrote: > * counter_to_rawmono64 > * counter_to_mono64 > * counter_to_realtime64 > > Enables drivers to translate a captured system clock counter to system > time. This is useful for network and audio devices that capture timestamps > in terms of both the system clock and device clock. Huh. So for counter_to_realtime64 & mono64, this seems to ignore the fact that the multiplier is constantly adjusted and corrected. So that calling the function twice with the same counter value may result in different returned values. I've not yet groked the whole patchset, but it seems like there needs to be some mechanism that ensures the counter value is captured and used in the same (or at least close) interval that the timekeeper data is valid for. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/