Re: [PATCH v3 1/3] drm/exynos: dp: add of_graph dt binding support for panel

[Javier Martinez Canillas <javier@osg.samsung.com>]

Hello Inki,

On 12/04/2015 11:57 AM, Inki Dae wrote:
> Hi Javier,
> 
> 2015-12-04 21:38 GMT+09:00 Javier Martinez Canillas <javier@osg.samsung.com>:
>> Hello Inki,
>>
>> On 12/04/2015 06:00 AM, Inki Dae wrote:
>>> Hi Javier,
>>>
>>> 2015년 12월 03일 22:55에 Javier Martinez Canillas 이(가) 쓴 글:
>>>> Hello Inki,
>>>>
>>>> I found that v2 of this patch is alredy in your exynos-drm for-next branch so
>>>> so I had to revert it in linux-next to apply this one to test. You shouldn't
>>>> push patches that were still not reviewed (specially the ones that weren't
>>>> tested like this one) to your branch that gets pulled by -next. The idea of
>>>> -next is to have some test coverage but it should be as stable as possible.
>>>
>>> exynos-drm/for-next branch is not really for-next branch. This branch is used
>>
>> Well, it is a for-next branch because is pulled by -next. It is listed in:
>> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/Next/Trees
>>
>> drm-exynos      git     git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos.git#exynos-drm/for-next
>>
>>> only for integration test. As you know, there are many exynos maintainers
>>> and they have their own repository. So we would need to test the integration.
>>
>> Integration testing is of course very needed and linux-next is for that but
>> what should be tested are the patches that are targeted to mainline.
>>
>>> For this, exynos-drm/for-next is merged to linux-next not Dave's tree.
>>> Only exynos-drm-next branch will be merged to Dave's tree so only reviewed and
>>> tested patches will be merged to exynos-drm-next.
>>>
>>
>> In that case, exynos-drm-next is what should be pulled by linux-next, no the
>> for-next branch. Linux-next is a simulation of what Torvalds would do next
>> so problems are found earlier, ideally before the patches land into mainline.
> 
> Seems I didn't comment enough. exynos-drm/for-next branch includes all
> patches of exynos-drm-next
> and actually, they keep same patches for most time but sometimes, I
> merge additional patches only to
> exynos-drm/for-next, which should be more tested with other trees
> before going to Dave's tree.
> 

Ok, but unreviewed and more importantly untested patches should not
go to to exynos-drm/for-next because those will be made available in
linux-next and can cause issues.

Only patches that are known to be good and have been reviewed/acked
should go there.

> One more thing, there is other difference between exynos-drm-next and
> exynos-drm/for-next.
> That is all patches of exynos-drm-next are merged on top of based on
> Dave's drm-next branch.
> On the other hand, all of exynos-drm/for-next are merged on top of
> mainline. So if exynos-drm-next

It's OK if you keep a different branch because you need a different
base before sending your pull request but IMHO the patches in both
branches should always be the same.

> is merged to linux-next then all patches will be conflicted with
> Dave's tree because his branch
> is also merged to linux-next.
>
> I'm not sure that other maintainers always keep only the for-next
> branch in their repository but
> in my case, I use exynos-drm/for-next branch for the test before going
> to drm-next.
> Anyway, exynos-drm-next will go to Dave's tree and then Dave's tree
> will also be pulled by
> linux-next, which would allow exynos-drm-next to be tested altogether
> again before going to mainline.
>

This should be a common problem for subsystems with different levels
of maintainership. I'm not a subsystem maintainer so I don't know how
this should be solved but I thought that git merge would take care
of this when both trees are pulled by linux-next.

Maybe Krzysztof can comment on this since he has to do the same for
the Exynos SoC support? He maintains a for-next branch and has to
send pull request to Kukjin (and sometimes may need to rebase on top
of Kukjin's tree) but both trees are pulled by linux-next to test.

> Thanks,
> Inki Dae
> 

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America