From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755558AbbAZQLe (ORCPT ); Mon, 26 Jan 2015 11:11:34 -0500 Received: from mx-guillaumet.finsecur.com ([91.217.234.131]:37363 "EHLO guillaumet.finsecur.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755187AbbAZQLa (ORCPT ); Mon, 26 Jan 2015 11:11:30 -0500 Date: Mon, 26 Jan 2015 17:11:24 +0100 From: Sylvain Rochet To: Nicolas Ferre Cc: Peter Rosin , Wenyou Yang , "linux@arm.linux.org.uk" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "alexandre.belloni@free-electrons.com" Message-ID: <20150126161124.GA24190@gradator.net> References: <1422265005-22937-1-git-send-email-wenyou.yang@atmel.com> <1422265139-23011-1-git-send-email-wenyou.yang@atmel.com> <20150126103605.GA20837@gradator.net> <54C6426E.9090808@atmel.com> <20150126134453.GA27559@gradator.net> <372b731350484f8ea1d29bd016421dfb@EMAIL.axentia.se> <54C66589.3040505@atmel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54C66589.3040505@atmel.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-SA-Exim-Connect-IP: 172.16.8.13 X-SA-Exim-Mail-From: sylvain.rochet@finsecur.com Subject: Re: [PATCH v2 02/12] pm: at91: Workaround DDRSDRC self-refresh bug with LPDDR1 memories. X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on guillaumet.finsecur.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Nicolas and Peter, On Mon, Jan 26, 2015 at 05:04:25PM +0100, Nicolas Ferre wrote: > Le 26/01/2015 16:58, Peter Rosin a écrit : > > Sylvain Rochet wrote: > >> Hello Nicolas, > >> > >> On Mon, Jan 26, 2015 at 02:34:38PM +0100, Nicolas Ferre wrote: > >>> Le 26/01/2015 11:36, Sylvain Rochet a écrit : > >>>> > >>>> I think we should explain we are dealing with an errata here, this > >>>> is not obvious at first sight, the patch summary may find its place > >>>> here :-) > >>> > >>> True but the problem is that this errata is not public yet, it will be > >>> in a couple of weeks. > >>> > >>> I have the feeling though that the commit message is pretty clear. > >>> We'll maybe add that it"s an actual errata. > >> > >> Humm, this is not what I meant actually. I only proposed a code source > >> comment explaining why this is done this way, the current patch summary > >> looked like it will be perfect between /* */ ;-) > > > > I did not want to fill up the source with wordy comments, and settled > > for a one-liner. I don't know much about the underlying reasons other > > than the fact that LPDDR1 mode of the controller isn't working properly > > in self-refresh and that the DDR2 spec is similar enough to work. > > > > The one-liner comment says about the same thing, but not with so > > many words. The comment does make it clear that the switch to DDR2 > > is intentional, and that is all that is needed as protection from some > > future cleanup. I mean, anyone seeing that comment and just erasing > > the whole thing without further investigation is not doing a very good > > job as there is no reason to intentionally switch from LPDDR1 mode to > > DDR2 mode, other that the fact that the LPDDR1 mode isn't working for > > some reason. That reason is not to be found in the commit message > > and I have no information to improve the situation. IMO, the only thing > > missing is a pointer to the as yet unreleased errata, which should explain > > the situation clearly for any and all interested parties. May I suggest that > > someone who cares sends a patch with the comment update when the > > errata is released? > > That's the option that I'll take. > > Let's go for it (and anyone remind me if I don't when the errata is > released). I fully agree with that, a pointer to a datasheet errata is exactly the same thing as explaining the issue. Sylvain