Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753835AbbBMTTX (ORCPT ); Fri, 13 Feb 2015 14:19:23 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:35282 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753756AbbBMTTT (ORCPT ); Fri, 13 Feb 2015 14:19:19 -0500 Message-ID: <1423855102.4182.63.camel@pengutronix.de> Subject: Re: [PATCH 12/14] ARM: dts: Introduce STM32F429 MCU From: Philipp Zabel To: Maxime Coquelin Cc: Jonathan Corbet , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Daniel Lezcano , Thomas Gleixner , Linus Walleij , Greg Kroah-Hartman , Jiri Slaby , Arnd Bergmann , Andrew Morton , "David S. Miller" , Mauro Carvalho Chehab , Joe Perches , Antti Palosaari , Tejun Heo , Will Deacon , Nikolay Borisov , Rusty Russell , Kees Cook , Michal Marek , "linux-doc@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-gpio@vger.kernel.org" , "linux-serial@vger.kernel.org" , Linux-Arch , "linux-api@vger.kernel.org" Date: Fri, 13 Feb 2015 20:18:22 +0100 In-Reply-To: References: <1423763164-5606-1-git-send-email-mcoquelin.stm32@gmail.com> <1423763164-5606-13-git-send-email-mcoquelin.stm32@gmail.com> <1423828078.4182.17.camel@pengutronix.de> <1423844735.4182.52.camel@pengutronix.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:96de:80ff:fec2:9969 X-SA-Exim-Mail-From: p.zabel@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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3975 Lines: 97 Am Freitag, den 13.02.2015, 17:41 +0100 schrieb Maxime Coquelin: > 2015-02-13 17:25 GMT+01:00 Philipp Zabel : > > Hi Maxime, > > > > Am Freitag, den 13.02.2015, 16:59 +0100 schrieb Maxime Coquelin: > >> Hi Philipp, > >> > >> 2015-02-13 12:47 GMT+01:00 Philipp Zabel : > >> > Hi Maxime, > >> > > >> > Am Donnerstag, den 12.02.2015, 18:46 +0100 schrieb Maxime Coquelin: > >> > [...] > >> >> + soc { > >> >> + reset_ahb1: reset@40023810 { > >> >> + #reset-cells = <1>; > >> >> + compatible = "st,stm32-reset"; > >> >> + reg = <0x40023810 0x4>; > >> >> + }; > >> >> + > >> >> + reset_ahb2: reset@40023814 { > >> >> + #reset-cells = <1>; > >> >> + compatible = "st,stm32-reset"; > >> >> + reg = <0x40023814 0x4>; > >> >> + }; > >> >> + > >> >> + reset_ahb3: reset@40023818 { > >> >> + #reset-cells = <1>; > >> >> + compatible = "st,stm32-reset"; > >> >> + reg = <0x40023818 0x4>; > >> >> + }; > >> >> + > >> >> + reset_apb1: reset@40023820 { > >> >> + #reset-cells = <1>; > >> >> + compatible = "st,stm32-reset"; > >> >> + reg = <0x40023820 0x4>; > >> >> + }; > >> >> + > >> >> + reset_apb2: reset@40023824 { > >> >> + #reset-cells = <1>; > >> >> + compatible = "st,stm32-reset"; > >> >> + reg = <0x40023824 0x4>; > >> >> + }; > >> > > >> > These are mostly consecutive, single registers. I wonder if these are > >> > part of the same IP block and thus should be grouped together into the > >> > same reset controller node? > >> > >> What I could to is to have two instances. One for AHB and one for APB domain. > >> Doing this, I will have one instance per domain, and only consecutive registers. > >> Is it fine for you? > > > > Looking at > > http://www.st.com/web/en/resource/technical/document/reference_manual/DM00031020.pdf > > Table 34 (RCC register map and reset values), I'd say there is a single > > "Reset and Clock Control" device at 0x40023800 - 0x40023884: > > > > soc { > > rcc: rcc@40023800 { > > #clock-cells = <1>; > > #reset-cells = <1>; > > compatible = "st,stm32-rcc"; > > reg = <0x40023800 0x84>; > > }; > > > > ... > > > > If you really want to describe the reset controller parts (offsets +0x10 > > to +0x24) in a separate node, I won't argue against it too long, > > although this is a somewhat arbitrary decision. > > > > In any case, the whole register at offset +0x1c is reserved, so there is > > no reason to split the reset controller. It is ok to have unused ranges > > as is already the case with reserved bits inside the used registers. > > Ok. I understand your point. > But it will be more difficult at usage, because the node referencing > the fourth reset bit of apb2 register will have to pass 164 as > parameter. > It is error prone IMHO. > > Other solution would be to add some defines for each reset line in the > DT-Bindings, as we do today for STi platform. > But it is giving an unneeded constraint between DT and reset trees. That is a bit unfortunate, but providing the named constants in include/dt-bindings/reset/ makes for a much better readable device tree, so I'd prefer that solution, even if it means having to coordinate pull requests. regards Philipp -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/