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@gmail.com:
On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang ykk@rock-chips.com 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:
- 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:
- 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.
- "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.
- 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