Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754888AbbHYBiB (ORCPT ); Mon, 24 Aug 2015 21:38:01 -0400 Received: from regular1.263xmail.com ([211.150.99.131]:38192 "EHLO regular1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754177AbbHYBh7 (ORCPT ); Mon, 24 Aug 2015 21:37:59 -0400 X-263anti-spam: KSV:0; X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED: 0 X-RL-SENDER: ykk@rock-chips.com X-FST-TO: andy.yan@rock-chips.com X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: ykk@rock-chips.com X-UNIQUE-TAG: <505a9cc4508d281820244cccf88c9c98> X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [PATCH v3 06/14] Documentation: drm/bridge: add document for analogix_dp To: Heiko Stuebner References: <1439995728-18046-1-git-send-email-ykk@rock-chips.com> <55DA9B72.1030804@samsung.com> <55DB1281.9070502@rock-chips.com> <18468783.Lfl8UEMQ1s@phil> 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 Esteva m , Jingoo Han , "linux-kernel@vger.kernel.org" , Kyungmin Park , Daniel Kurtz , Philipp Zabel , Kumar Gala , Joe Perches , Andy Yan From: Yakir Yang Message-ID: <55DBC6C9.8030705@rock-chips.com> Date: Tue, 25 Aug 2015 09:37:13 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <18468783.Lfl8UEMQ1s@phil> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3599 Lines: 89 Hi Heiko, 在 2015/8/24 21:03, Heiko Stuebner 写道: > 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); > } > Wow, thanks a lot for your explain and code, it do help me to understand this suggest rightly :-) Thanks, - Yakir > > > > > -- 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/