From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756086Ab2JJRJc (ORCPT ); Wed, 10 Oct 2012 13:09:32 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:59202 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752757Ab2JJRJa (ORCPT ); Wed, 10 Oct 2012 13:09:30 -0400 Message-ID: <5075ABB8.103@gmail.com> Date: Wed, 10 Oct 2012 12:09:12 -0500 From: Rob Herring User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 MIME-Version: 1.0 To: Stephen Warren CC: Jon Loeliger , Michal Marek , David Gibson , devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org, Stephen Warren Subject: Re: dtc: import latest upstream dtc References: <1348867559-2495-1-git-send-email-swarren@wwwdotorg.org> <5069C042.40209@gmail.com> <5069C11C.6040505@wwwdotorg.org> <5069D946.1060502@gmail.com> <5069E1F0.5070902@wwwdotorg.org> <50749441.8030307@wwwdotorg.org> In-Reply-To: <50749441.8030307@wwwdotorg.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/09/2012 04:16 PM, Stephen Warren wrote: > On 10/01/2012 12:39 PM, Jon Loeliger wrote: >>> >>> What more do you think needs discussion re: dtc+cpp? >> >> How not to abuse the ever-loving shit out of it? :-) > > Perhaps we can just handle this through the regular patch review > process; I think it may be difficult to define and agree upon exactly > what "abuse" means ahead of time, but it's probably going to be easy > enough to recognize it when one sees it? Rather than repeating things over and over in reviews, we should document at least rules we can easily agree on and then add to it when people get "creative." Also, I can't keep up with every single binding review as is, and this could just add another level of complexity to the review. A few off the top of my head and from the thread discussion: - Headers must be self contained with no outside (i.e. libc, kernel, etc.) header dependencies. - No kernel kconfig option usage - No gcc built-in define usage - No unused items (i.e. externs, structs, etc.) - No macro concatenation - No macros for strings or property names Do we further restrict things to say defines are only numbers? One could start to define complex macros to build the nodes themselves. If each platform does this slightly differently, it will become difficult to review and maintain. Then we will be doing dts consolidation. The fact that we have some fixed structure and each SOC is not free to do things their own way makes things easier to maintain. You don't have that in the kernel across platforms. For example, look how register defines and static mappings or platform device creation are done. They are all similar, but yet slightly different. That makes doing changes across platforms more difficult. > I imagine the most common usage will simply be a bunch of: > > #define TEGRA_GPIO_PB0 32 > #define TEGRA_GPIO_INT_LEVEL_LOW 8 > > / { > xxx { > interrupts = ; > > and similarly, simple math: > > something = <((FOO << XXX_SHIFT) | (BAR << YYY_SHIFT))>; > These are all perfectly fine and sane use, but if we don't restrict things then the next step is this: #define PROP_SOMETHING(v) (something = <(v)>) Rob