On 24.08.2015 21:48, Yakir Yang wrote: > Hi Krzysztof, > > 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 <robherring2@xxxxxxxxx>: >>>>> On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang <ykk@xxxxxxxxxxxxxx> >>>>> 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. Right, the focus is on the driver. > If so the new analogix dp driver > should keep > the "samsung,color-space", rather then just mark it with [DEPRECATED] flag. If you are replacing a binding/property then it should be marked deprecated. This means that the old property is still working but new users of it should not be added. > > 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", It looks wrong because it breaks backward compatibility with existing DTB. As I said before: >>> 1. Provide backward compatibility. Mark old properties >>> as deprecated but still support them. > And actually @Rob have suggest me to remove the prefix, just use > "color-space" here. For new bindings I don't mind. But please remember about existing users, existing DTB and bisectability. > >> >>> Let me show same examples, make >>> me understand your suggest rightly. >> exynos-dp already contains deprecated properties. Other ways of doing >> this would be: >> Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt >> Documentation/devicetree/bindings/rtc/s3c-rtc.txt >> >> It depends up to you. The "touchscreen" looks good because it organizes >> old properties in a common section. In case of exynos-dp.txt you can add >> at beginning of file information about new bindings and mark everything >> deprecated. > > Whoops, thanks for your remind, I prefer the "touchscreen" style. > >>> 1. "samsung,ycbcr-coeff" is abandoned in latest analogix-dp driver, >>> absolutely >>> I should not carry this to analogix-dp.txt document. But I should >>> keep this in >>> exynos-dp.txt document, and mark them with an little >>> "deprecated" flag. >>> >>> [Documentation/devicetree/bindings/video/exynos_dp.txt] >>> Required properties for dp-controller: >>> [...] >>> -samsung,ycbcr-coeff (DEPRECATED): >>> YCbCr co-efficients for input video. >>> COLOR_YCBCR601 = 0, COLOR_YCBCR709 = 1 >>> >>> Is it right ? >> Yes, this is right. >> >>>> 2. Separate all DTS changes to a separate patch, unless bisectability >>>> would be hurt. Anyway you should prepare it in a such way that >>>> separation would be possible without breaking bisectability. >>> So I should separate this patch into two parts, one is name "Document:", >>> the other is "ARM: dts: ". >> Yes. >> >>> Honestly, I don't understand what the "bisectability" means in this >>> case. >> I was referring to bisectability in general. The patchset should be >> fully bisectable which means that it does not introduce any issues >> during "git bisect". This effectively means that at each intermediate >> step (after applying each patch, one by one) every existing stuff works >> the same as previously without any regression. Including booting with >> old DTB. > > Oh, thanks for your careful explain, so I guess your first comment is > talking about > the "bisectability" that if I only apply the 01 - 05 patches, kernel > could not bootup > normally, cause driver need "analogix,color-space" but DTB only have > "samsung,color-space". Right. In the same time please remember that kernel may be booted with old DTB. Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
