From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933245AbbIUXMh (ORCPT ); Mon, 21 Sep 2015 19:12:37 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:56281 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932657AbbIUXMg (ORCPT ); Mon, 21 Sep 2015 19:12:36 -0400 Date: Mon, 21 Sep 2015 16:12:35 -0700 (PDT) Message-Id: <20150921.161235.605756522215336833.davem@davemloft.net> To: robert.jarzmik@free.fr Cc: samuel@sortiz.org, petr.cvek@tul.cz, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, arnd@arndb.de Subject: Re: [PATCH v2 1/3] net: irda: pxaficp_ir: use sched_clock() for time management From: David Miller In-Reply-To: <87si6br8ev.fsf@belgarion.home> References: <87eghyso6u.fsf@belgarion.home> <20150917.145106.1238429841434804906.davem@davemloft.net> <87si6br8ev.fsf@belgarion.home> 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, 21 Sep 2015 16:12:36 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Robert Jarzmik Date: Fri, 18 Sep 2015 18:36:56 +0200 > Which brings me to wonder which is the more correct : > (a) replace to reproduce the same calculation > Previously mtt was compared to a difference of 76ns steps (as 307ns / 4 = > 76ns): > while ((sched_clock() - si->last_clk) * 76 < mtt) > > (b) change the calculation assuming mtt is in microseconds : > while ((sched_clock() - si->last_clk) * 1000 < mtt) > > I have no IRDA protocol knowledge so unless someone points me to the correct > calculation I'll try my luck with (b). "a" would be "safer" and less likely to break anything, although as you say "b" might be more correct.