Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754562AbbHXNDn (ORCPT ); Mon, 24 Aug 2015 09:03:43 -0400 Received: from gloria.sntech.de ([95.129.55.99]:44838 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754378AbbHXNDl convert rfc822-to-8bit (ORCPT ); Mon, 24 Aug 2015 09:03:41 -0400 From: Heiko Stuebner To: Yakir Yang Cc: Krzysztof Kozlowski , Rob Herring , Sean Paul , Takashi Iwai , dri-devel , Andrzej Hajda , Gustavo Padovan , "linux-samsung-soc@vger.kernel.org" , Vincent Palatin , Kishon Vijay Abraham I , linux-rockchip@lists.infradead.org, Russell King , Thierry Reding , "devicetree@vger.kernel.org" , Pawel Moll , Ian Campbell , David Airlie , Doug Anderson , Inki Dae , Ajay kumar , Rob Herring , "linux-arm-kernel@lists.infradead.org" , Mark Yao , Fabio Estevam , Jingoo Han , "linux-kernel@vger.kernel.org" , Kyungmin Park , Daniel Kurtz , Philipp Zabel , Kumar Gala , Joe Perches , Andy Yan Subject: Re: [PATCH v3 06/14] Documentation: drm/bridge: add document for analogix_dp Date: Mon, 24 Aug 2015 15:03:05 +0200 Message-ID: <18468783.Lfl8UEMQ1s@phil> User-Agent: KMail/4.14.1 (Linux/4.1.0-1-amd64; KDE/4.14.2; x86_64; ; ) In-Reply-To: <55DB1281.9070502@rock-chips.com> References: <1439995728-18046-1-git-send-email-ykk@rock-chips.com> <55DA9B72.1030804@samsung.com> <55DB1281.9070502@rock-chips.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3411 Lines: 82 Hi Yakir, Am Montag, 24. August 2015, 20:48:01 schrieb Yakir Yang: > 在 08/24/2015 12:20 PM, Krzysztof Kozlowski 写道: > > On 24.08.2015 11:42, Yakir Yang wrote: > >> Hi Krzysztof, > >> > >> 在 08/23/2015 07:43 PM, Krzysztof Kozlowski 写道: > >>> 2015-08-24 8:23 GMT+09:00 Rob Herring : > >>>> On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang wrote: > >>>>> Analogix dp driver is split from exynos dp driver, so we just > >>>>> make an copy of exynos_dp.txt, and then simplify exynos_dp.txt > >>>>> > >>>>> Beside update some exynos dtsi file with the latest change > >>>>> according to the devicetree binding documents. > >>>> > >>>> You can't just change the exynos bindings and break compatibility. Is > >>>> there some agreement with exynos folks to do this? > >>> > >>> No, there is no agreement. This wasn't even sent to Exynos maintainers. > >> > >> Sorry about this one, actually I have add Exynos maintainers in version > >> 1 & version 2, > >> but lose some maintainers in version 3, I would fix it in bellow > >> versions. > >> > >>> Additionally the patchset did not look interesting to me because of > >>> misleading subject - Documentation instead of "ARM: dts:". > >>> > >>> Yakir, please: > >>> 1. Provide backward compatibility. Mark old properties as deprecated > >>> but still support them. > >> > >> Do you mean that I should keep the old properties declare in > >> exynos-dp.txt, > >> but just mark them as deprecated flag. > > > > That is one of ways how to do this. However more important is that > > driver should still support old bindings so such code: > > - if (of_property_read_u32(dp_node, "samsung,color-space", > > + if (of_property_read_u32(dp_node, "analogix,color-space", > > > > is probably wrong. Will the driver support old DTB in the same way as it > > was supporting before the change? > > Okay, I got your means. So document is not the focus, the most important > is that > driver should support the old dts prop. If so the new analogix dp driver > should keep > the "samsung,color-space", rather then just mark it with [DEPRECATED] flag. > > But from your follow suggest, I think you agree to update driver code, > and just mark > old prop with deprecated flag. If so I think such code would not be wrong > > - if (of_property_read_u32(dp_node, "samsung,color-space", > + if (of_property_read_u32(dp_node, "analogix,color-space", In a generic driver, the property should have either none, or the analogix prefix. But DT-properties need to be backwards compatible, meaning an older Exynos devicetree should run unmodified with a newer kernel. So the common course of action is to mark the old one as deprecated but still test for both, so something like: if (of_property_read_u32(dp_node, "analogix,color-space", &dp_video_config->color_space)) if (of_property_read_u32(dp_node, "samsung,color-space", &dp_video_config->color_space)) { dev_err(dev, "failed to get color-space\n"); return ERR_PTR(-EINVAL); } -- 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/