From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yakir Yang Subject: Re: [PATCH v3 06/14] Documentation: drm/bridge: add document for analogix_dp Date: Tue, 25 Aug 2015 09:37:13 +0800 Message-ID: <55DBC6C9.8030705@rock-chips.com> References: <1439995728-18046-1-git-send-email-ykk@rock-chips.com> <55DA9B72.1030804@samsung.com> <55DB1281.9070502@rock-chips.com> <18468783.Lfl8UEMQ1s@phil> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <18468783.Lfl8UEMQ1s@phil> Sender: linux-samsung-soc-owner@vger.kernel.org To: Heiko Stuebner 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-kern List-Id: devicetree@vger.kernel.org Hi Heiko, =E5=9C=A8 2015/8/24 21:03, Heiko Stuebner =E5=86=99=E9=81=93: > Hi Yakir, > > Am Montag, 24. August 2015, 20:48:01 schrieb Yakir Yang: >> =E5=9C=A8 08/24/2015 12:20 PM, Krzysztof Kozlowski =E5=86=99=E9=81=93= : >>> On 24.08.2015 11:42, Yakir Yang wrote: >>>> Hi Krzysztof, >>>> >>>> =E5=9C=A8 08/23/2015 07:43 PM, Krzysztof Kozlowski =E5=86=99=E9=81= =93: >>>>> 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 compatibilit= y. Is >>>>>> there some agreement with exynos folks to do this? >>>>> No, there is no agreement. This wasn't even sent to Exynos mainta= iners. >>>> Sorry about this one, actually I have add Exynos maintainers in ve= rsion >>>> 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 depreca= ted >>>>> 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 impor= tant >> is that >> driver should support the old dts prop. If so the new analogix dp dr= iver >> 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 cod= e, >> 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 ana= logix > 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 b= ut 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 understan= d this suggest rightly :-) Thanks, - Yakir > > > > >