From: k.kozlowski@samsung•com (Krzysztof Kozlowski)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 06/14] Documentation: drm/bridge: add document for analogix_dp
Date: Tue, 25 Aug 2015 08:49:36 +0900 [thread overview]
Message-ID: <55DBAD90.3040901@samsung.com> (raw)
In-Reply-To: <55DB1281.9070502@rock-chips.com>
On 24.08.2015 21:48, Yakir Yang wrote:
> Hi Krzysztof,
>
> ? 08/24/2015 12:20 PM, Krzysztof Kozlowski ??:
>> On 24.08.2015 11:42, Yakir Yang wrote:
>>> Hi Krzysztof,
>>>
>>> ? 08/23/2015 07:43 PM, Krzysztof Kozlowski ??:
>>>> 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:
>>>> 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
next prev parent reply other threads:[~2015-08-24 23:49 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-19 14:48 [PATCH v3 0/14] Add Analogix Core Display Port Driver Yakir Yang
2015-08-19 14:49 ` [PATCH v3 01/14] drm: exynos/dp: fix code style Yakir Yang
2015-08-19 14:49 ` [PATCH v3 02/14] drm: exynos/dp: convert to drm bridge mode Yakir Yang
2015-08-19 14:50 ` [PATCH v3 04/14] drm: bridge/analogix_dp: dynamic parse sync_pol & interlace & colorimetry Yakir Yang
2015-08-19 14:50 ` [PATCH v3 05/14] drm: bridge/analogix_dp: fix link_rate & lane_count bug Yakir Yang
2015-08-20 7:22 ` Jingoo Han
2015-08-20 8:04 ` Yakir Yang
2015-08-19 14:50 ` [PATCH v3 06/14] Documentation: drm/bridge: add document for analogix_dp Yakir Yang
2015-08-23 23:23 ` Rob Herring
2015-08-24 0:43 ` Krzysztof Kozlowski
[not found] ` <55DA8486.1000803@rock-chips.com>
2015-08-24 4:20 ` Krzysztof Kozlowski
2015-08-24 12:48 ` Yakir Yang
2015-08-24 13:03 ` Heiko Stuebner
2015-08-25 1:37 ` Yakir Yang
2015-08-24 23:49 ` Krzysztof Kozlowski [this message]
2015-08-25 1:33 ` Yakir Yang
2015-08-25 1:35 ` Krzysztof Kozlowski
2015-08-24 7:40 ` Jingoo Han
2015-08-24 12:55 ` Yakir Yang
2015-08-24 12:57 ` Russell King - ARM Linux
2015-08-24 14:48 ` Rob Herring
2015-08-24 16:16 ` Heiko Stuebner
2015-08-25 1:21 ` Yakir Yang
2015-08-25 9:12 ` Thierry Reding
2015-08-25 9:29 ` Russell King - ARM Linux
2015-08-25 10:40 ` Thierry Reding
2015-08-25 10:52 ` Russell King - ARM Linux
[not found] ` <55DC383F.4000103@rock-chips.com>
2015-08-25 10:06 ` Thierry Reding
2015-08-25 9:15 ` Thierry Reding
2015-08-25 13:27 ` Rob Herring
[not found] ` <55DC7211.9080601@rock-chips.com>
2015-08-25 14:16 ` Thierry Reding
2015-08-25 9:58 ` Thierry Reding
[not found] ` <55DC75C8.209@rock-chips.com>
2015-08-25 14:21 ` Thierry Reding
2015-08-25 15:57 ` Russell King - ARM Linux
2015-08-19 14:50 ` [PATCH v3 07/14] drm: rockchip/dp: add rockchip platform dp driver Yakir Yang
2015-08-19 14:51 ` [PATCH v3 08/14] phy: Add driver for rockchip Display Port PHY Yakir Yang
2015-08-20 4:40 ` Kishon Vijay Abraham I
2015-08-19 14:51 ` [PATCH v3 09/14] drm: bridge/analogix_dp: add platform device type support Yakir Yang
2015-08-19 14:51 ` [PATCH v3 10/14] drm: bridge: analogix_dp: add some rk3288 special registers setting Yakir Yang
2015-08-19 14:51 ` [PATCH v3 11/14] drm: bridge: analogix_dp: try force hpd after plug in lookup failed Yakir Yang
2015-08-19 14:52 ` [PATCH v3 12/14] drm: bridge/analogix_dp: expand the delay time for hpd detect Yakir Yang
2015-08-20 6:11 ` Jingoo Han
2015-08-20 8:02 ` Yakir Yang
2015-08-19 14:52 ` [PATCH v3 13/14] drm: bridge/analogix_dp: move hpd detect to connector detect function Yakir Yang
2015-08-20 7:49 ` Jingoo Han
2015-08-20 8:18 ` Yakir Yang
2015-08-19 14:52 ` [PATCH v3 14/14] drm: bridge/analogix_dp: add edid modes parse in get_modes method Yakir Yang
2015-08-19 23:54 ` [PATCH v3 0/14] Add Analogix Core Display Port Driver Dave Airlie
2015-08-20 1:02 ` Yakir Yang
2015-08-20 4:29 ` Archit Taneja
2015-08-20 5:54 ` Jingoo Han
2015-08-20 6:23 ` Yakir Yang
2015-08-20 6:55 ` Jingoo Han
2015-08-20 8:03 ` Yakir Yang
2015-08-21 8:20 ` Jingoo Han
[not found] ` <55D6F6F8.70504@rock-chips.com>
[not found] ` <8384E112-E1F4-4CD3-85BF-A2A25989783F@gmail.com>
2015-08-21 13:16 ` Thierry Reding
2015-08-30 12:16 ` Romain Perier
2015-08-31 2:40 ` Yakir Yang
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