From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934125AbbIVTdZ (ORCPT ); Tue, 22 Sep 2015 15:33:25 -0400 Received: from smtp01.smtpout.orange.fr ([80.12.242.123]:21749 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933528AbbIVTdX (ORCPT ); Tue, 22 Sep 2015 15:33:23 -0400 X-ME-Helo: belgarion X-ME-Auth: amFyem1pay5yb2JlcnRAb3JhbmdlLmZy X-ME-Date: Tue, 22 Sep 2015 21:33:22 +0200 X-ME-IP: 109.222.127.209 From: Robert Jarzmik To: David Miller 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 References: <87eghyso6u.fsf@belgarion.home> <20150917.145106.1238429841434804906.davem@davemloft.net> <87si6br8ev.fsf@belgarion.home> <20150921.161235.605756522215336833.davem@davemloft.net> X-URL: http://belgarath.falguerolles.org/ Date: Tue, 22 Sep 2015 21:27:51 +0200 In-Reply-To: <20150921.161235.605756522215336833.davem@davemloft.net> (David Miller's message of "Mon, 21 Sep 2015 16:12:35 -0700 (PDT)") Message-ID: <87r3lqp83s.fsf@belgarion.home> User-Agent: Gnus/5.130008 (Ma Gnus v0.8) Emacs/24.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Miller writes: > 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. Indeed. Well, let me try (b) then. I'll add in the commit message the timings change, and if anybody complains a regression pops out, I'll provide a patch to fallback to (a). Cheers. -- Robert