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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 B39C1C43381 for ; Wed, 20 Feb 2019 10:52:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81A492183F for ; Wed, 20 Feb 2019 10:52:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727675AbfBTKw6 (ORCPT ); Wed, 20 Feb 2019 05:52:58 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:35539 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726317AbfBTKw5 (ORCPT ); Wed, 20 Feb 2019 05:52:57 -0500 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gwPUg-0005jz-Sr; Wed, 20 Feb 2019 11:52:50 +0100 Received: from mfe by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1gwPUf-0004m4-K2; Wed, 20 Feb 2019 11:52:49 +0100 Date: Wed, 20 Feb 2019 11:52:49 +0100 From: Marco Felsch To: Aisheng Dong Cc: Anson Huang , "robh+dt@kernel.org" , "mark.rutland@arm.com" , "shawnguo@kernel.org" , "s.hauer@pengutronix.de" , "kernel@pengutronix.de" , "festevam@gmail.com" , "ulf.hansson@linaro.org" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , dl-linux-imx Subject: Re: [PATCH] dt-bindings: imx: update scu resource id headfile Message-ID: <20190220105249.u2hcvk6ut3cycvqs@pengutronix.de> References: <1550566601-11497-1-git-send-email-Anson.Huang@nxp.com> <20190219125211.2pg2bqxner4klcb5@pengutronix.de> <20190219144808.qqpaubjcsb4huoml@pengutronix.de> <20190220081650.cu3yzausx55jefb6@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 11:37:54 up 32 days, 15:19, 42 users, load average: 0.09, 0.05, 0.04 User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: mfe@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Aisheng, On 19-02-20 09:49, Aisheng Dong wrote: > > From: Marco Felsch [mailto:m.felsch@pengutronix.de] > > Sent: Wednesday, February 20, 2019 4:17 PM > > On 19-02-20 03:38, Aisheng Dong wrote: > > > [...] > > > > > > > > I don't like droping some ID's (e.g. IMX_SC_R_DC_0_CAPTURE0) by > > > > > mark them as unused or even worse give them a other meaning. IMHO > > > > > the scu-api should be stable since day 1 and the ID's should only be > > extended. > > > > > Marking ID's as deprecated is much better than moving them around. > > > > > > > > I agree the SCU APIs should be stable since day 1 and the ID should > > > > ONLY be extended, but that is the best cases, the reality is, there > > > > are different SoCs/Revision, some revisions may remove the resources > > > > ID defined in pre-coded SCU firmware, like the > > > > IMX_SC_R_DC_0_CAPTURE0 etc., so SCU APIs removes them after real > > > > silicon arrived, now latest SCU firmware marks them as UNUSED, they > > > > could be replaced by some other new resources in later new SoC, I am > > > > NOT sure, but if it happens, this resource ID table should be > > > > updated anyway, leaving the out-of-date resource ID table there will have > > issues, since it is NOT sync with SCU firmware. > > > > > > > > So how to resolve such issue? We hope the SCU firmware should be > > > > stable since day 1, but the truth is NOT, could be still some > > > > updates but NOT very often. And I believe the updates will NOT break old > > kernel version. > > > > Hi Anson, > > > > Please don't mix the dt-bindings and the kernel related stuff. > > Unfortunately the bindings are within the kernel repo which in fact is great for > > us kernel developer but the bindings are also used in other projects such as > > barebox or other kernels (don't know the BSD guys). So you can't ensure that > > your change will break something. Please keep that in mind. > > > > IMHO solving that issue should be done by the scu firmware. I tought the scu is > > a cortex-m4 with a bunch of embedded flash and ram (I don't know that much > > about the scu since it is closed/black-boxed). Why do you don't use a > > translation table within the scu? As I said earlier I don't like the redefinition of > > ID's since they are now part of the dt-bindings. > > The bindings can store up to 32bit values which is a large number ;) IMHO > > wasting some ID's in favour of stability is a better solution. > > > > As far as I know, those remove resource IDs are pre-defined and has never been used > and won't be used anymore by SC firmware. (Anson can double check it) > So I think it's safe to remove them or mark them as deprecated. I think marking them as deprecated by a commentar is better than redefining bits to be unused. As I said the bindings not only linux related they are used in other projects too. > > Personally I may prefer to remove them as they never worked to avoid confusing, > especially at this early stage for mx8. So why they are there if they never worked? Wouldn't it a better approach to start with a basic and working ID file and extend this rather than adding id's because maybe the will work.. Sorry but this seems wrong to me too. I know the approach from driver development, adding a driver specific *_reg.h file and later figuring out that those bits won't work as aspected. As I said this will be driver and only linux related so we can change them as many times as we want. But in your case we are talking about dt-bindings and this approach won't work. Regards, Marco > > Regards > Dong Aisheng > -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |