From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4205FC2BB1D for ; Fri, 17 Apr 2020 07:02:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 286D521D91 for ; Fri, 17 Apr 2020 07:02:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728590AbgDQHCo (ORCPT ); Fri, 17 Apr 2020 03:02:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728098AbgDQHCn (ORCPT ); Fri, 17 Apr 2020 03:02:43 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2916C061A0C; Fri, 17 Apr 2020 00:02:42 -0700 (PDT) Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:b93f:9fae:b276:a89a]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 03D7F2A249D; Fri, 17 Apr 2020 08:02:39 +0100 (BST) Date: Fri, 17 Apr 2020 09:02:34 +0200 From: Boris Brezillon To: "Ramuthevar, Vadivel MuruganX" Cc: Martin Blumenstingl , anders.roxell@linaro.org, andriy.shevchenko@intel.com, arnd@arndb.de, brendanhiggins@google.com, cheol.yong.kim@intel.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, masonccyang@mxic.com.tw, miquel.raynal@bootlin.com, piotrs@cadence.com, qi-ming.wu@intel.com, richard@nod.at, robh+dt@kernel.org, tglx@linutronix.de, vigneshr@ti.com Subject: Re: [PATCH v1 2/2] mtd: rawnand: Add NAND controller support on Intel LGM SoC Message-ID: <20200417090234.059418f6@collabora.com> In-Reply-To: <003fa549-08c5-5867-2b02-54b483c16465@linux.intel.com> References: <20200414022433.36622-3-vadivel.muruganx.ramuthevar@linux.intel.com> <20200415220533.733834-1-martin.blumenstingl@googlemail.com> <20200416113822.2ef326cb@collabora.com> <18568cf6-2955-472e-7b68-eb35e654a906@linux.intel.com> <20200416122619.2c481792@collabora.com> <20200416131725.51259573@collabora.com> <20200416135711.039ba85c@collabora.com> <003fa549-08c5-5867-2b02-54b483c16465@linux.intel.com> Organization: Collabora X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 17 Apr 2020 13:21:39 +0800 "Ramuthevar, Vadivel MuruganX" wrote: > Hi Boris, > > On 16/4/2020 7:57 pm, Boris Brezillon wrote: > > On Thu, 16 Apr 2020 19:38:03 +0800 > > "Ramuthevar, Vadivel MuruganX" > > wrote: > > > >> On 16/4/2020 7:17 pm, Boris Brezillon wrote: > >>> On Thu, 16 Apr 2020 18:40:53 +0800 > >>> "Ramuthevar, Vadivel MuruganX" > >>> wrote: > >>> > >>>>>>> we'll be happy to have one more of the existing driver converted to > >>>>>>> ->exec_op() ;-). > >>>>>> I have completely adapted to ->exec_op() hook up to replace the legacy > >>>>>> call-back. > >>>>> I suspect porting what you've done to the xway driver shouldn't be too > >>>>> complicated. > >>>> Not ported from xway_nand.c driver , we have developed from the scratch > >>>> to make it work on > >>>> Intel LGM SoC , it's new x86 ATOM based SoC, IP itself completely > >>>> different and most of the registers won't match. > >>>> if we port then it would be ugly and also what are the problem may occur > >>>> we do not know. > >>> Sorry but IMO they look similar enough to try to merge them. > >> Thanks! Boris, need suggestion from you since you are maintainer and > >> also expertise on mtd-subsystem. > > I *was* the maintainer :). > > > >> There are different features involved and lines of code is more, if we > >> add new driver patches over xway-nand driver > > How about retro-fitting the xway logic into your driver then? I mean, > > adding a 100 lines of code to your driver to get rid of the 500+ lines > > we have in xway_nand.c is still a win. > > > >> is completely looks ugly and it may disturb the existing functionality > >> as well since we don't have platform to validate:'(. > > How ugly? Can you show us? Maybe we can come with a solution to make it > > less ugly. > > > > As for the testing part, there are 4 scenarios: > > > > 1/ Your changes work perfectly fine on older platforms. Yay \o/! > > 2/ You break the xway driver and existing users notice it before this > > series gets merged. Now you found someone to validate your changes. > > 3/ You break the xway driver and none of the existing users notice it > > before the driver is merged, but they notice it afterwards. Too bad > > this happened after we've merged the driver, but now you've found > > someone to help you fix the problem :P. > > 4/ You break things for old platforms but no one ever complains about > > it, either because there's no users left or because they never > > update their kernels. In any case, that's no longer your problem. > > Someone will remove those old platforms one day and get rid of the > > unneeded code in the NAND driver. > > > > What's more likely to happen is #3 or #4, and I think the NAND > > maintainer would be fine with both. > > > > Note that the NAND subsystem is full of unmaintained legacy drivers, so > > every time we see someone who could help us get rid or update one of > > them we have to take this opportunity. > Agreed!, Thank you very much for the suggestions and clear inputs. > To proceed further, can you please share your inputs to dividing the tasks > and patches to be sent if possible. Let's start with the new version you were about to post. We'll see how we can merge both drivers based on that.