From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751031AbdASHz2 (ORCPT ); Thu, 19 Jan 2017 02:55:28 -0500 Received: from mail.free-electrons.com ([62.4.15.54]:60275 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750717AbdASHzZ (ORCPT ); Thu, 19 Jan 2017 02:55:25 -0500 Date: Thu, 19 Jan 2017 08:53:03 +0100 From: Boris Brezillon To: Rob Herring Cc: Thomas Petazzoni , Marek Vasut , Mark Rutland , devicetree@vger.kernel.org, Guochun Mao , Richard Weinberger , Russell King , linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, Matthias Brugger , linux-mediatek@lists.infradead.org, Cyrille Pitchen , Brian Norris , David Woodhouse , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v1 2/2] arm: dts: mt2701: add nor flash node Message-ID: <20170119085303.24b8d462@bbrezillon> In-Reply-To: <20170118222010.ivc6jxpnrumemvdf@rob-hp-laptop> References: <20170113172825.75d545a3@bbrezillon> <86c997be-f500-eaa1-3ba5-d21cff6223b7@gmail.com> <20170113175628.1793f433@bbrezillon> <0fafcd8d-cf99-de6b-728f-5e3637810b68@gmail.com> <20170114092958.022f2fc8@bbrezillon> <20170116094032.6f471f11@bbrezillon> <20170117143650.5db87148@free-electrons.com> <20170118222010.ivc6jxpnrumemvdf@rob-hp-laptop> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 18 Jan 2017 16:20:10 -0600 Rob Herring wrote: > On Tue, Jan 17, 2017 at 02:36:50PM +1100, Thomas Petazzoni wrote: > > Hello, > > > > (Side note: you guys should learn about stripping irrelevant parts of > > an e-mail when replying!) > > > > On Mon, 16 Jan 2017 09:40:32 +0100, Boris Brezillon wrote: > > > > > > Well this is OK I guess, but then you can also use "mediatek,mt8173-nor" > > > > as the oldest supported compatible and be done with it, no ? It looks a > > > > bit crappy though, I admit that ... > > > > > > Let's stop bikeshedding and wait for DT maintainers feedback > > > before taking a decision ;-). > > > > > > Rob, Mark, any opinion? > > > > Sigh, is how to do compatibles really not yet understood? Apparently not, and I fear this is not the last misunderstanding on my side ;-). > > > I agree that a clarification would be good. There are really two > > options: > > > > 1. Have two compatible strings in the DT, the one that matches the > > exact SoC where the IP is found (first compatible string) and the > > one that matches some other SoC where the same IP is found (second > > compatible string). Originally, Linux only supports the second > > compatible string in its device driver, but if it happens that a > > difference is found between two IPs that we thought were the same, > > we can add support for the first compatible string in the driver, > > with a slightly different behavior. > > This. And no wildcards in the compatible string. > > > 2. Have a single compatible string in the DT, matching the exact SoC > > where the IP is found. This involves adding immediately this > > compatible string in the corresponding driver. > > I wouldn't object to this from a DT perspective as I have no clue > generally if IP blocks are "the same" or not. Subsystem maintainers will > object though. > > > I've not really been able to figure out which of the two options is the > > most future-proof/appropriate. > > They are both future-proof. #2 has the disadvantage of requiring a > kernel update for a new SoC. > > Rob