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Subject: Re: [PATCH 00/49] DRM driver for Hikey 970
From:   Nicolas Dufresne <nicolas@ndufresne.ca>
To:     Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        Dave Airlie <airlied@gmail.com>
Cc:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        David Airlie <airlied@linux.ie>,
        Wanchun Zheng <zhengwanchun@hisilicon.com>,
        linuxarm@huawei.com, dri-devel <dri-devel@lists.freedesktop.org>,
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        Sam Ravnborg <sam@ravnborg.org>,
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        <linaro-mm-sig@lists.linaro.org>, Rob Herring <robh+dt@kernel.org>,
        mauro.chehab@huawei.com, Rob Clark <robdclark@chromium.org>,
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Date:   Wed, 26 Aug 2020 10:44:28 -0400
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Le mardi 25 août 2020 à 13:30 +0200, Mauro Carvalho Chehab a écrit :
> Em Tue, 25 Aug 2020 05:29:29 +1000
> Dave Airlie <airlied@gmail.com> escreveu:
> 
> > On Thu, 20 Aug 2020 at 20:02, Laurent Pinchart
> > <laurent.pinchart@ideasonboard.com> wrote:
> > > Hi Mauro,
> > > 
> > > On Thu, Aug 20, 2020 at 09:03:26AM +0200, Mauro Carvalho Chehab wrote:  
> > > > Em Wed, 19 Aug 2020 12:52:06 -0700 John Stultz escreveu:  
> > > > > On Wed, Aug 19, 2020 at 8:31 AM Laurent Pinchart wrote:  
> > > > > > On Wed, Aug 19, 2020 at 05:21:20PM +0200, Sam Ravnborg wrote:  
> > > > > > > On Wed, Aug 19, 2020 at 01:45:28PM +0200, Mauro Carvalho Chehab wrote:  
> > > > > > > > This patch series port the out-of-tree driver for Hikey 970 (which
> > > > > > > > should also support Hikey 960) from the official 96boards tree:
> > > > > > > > 
> > > > > > > >    https://github.com/96boards-hikey/linux/tree/hikey970-v4.9
> > > > > > > > 
> > > > > > > > Based on his history, this driver seems to be originally written
> > > > > > > > for Kernel 4.4, and was later ported to Kernel 4.9. The original
> > > > > > > > driver used to depend on ION (from Kernel 4.4) and had its own
> > > > > > > > implementation for FB dev API.
> > > > > > > > 
> > > > > > > > As I need to preserve the original history (with has patches from
> > > > > > > > both HiSilicon and from Linaro),  I'm starting from the original
> > > > > > > > patch applied there. The remaining patches are incremental,
> > > > > > > > and port this driver to work with upstream Kernel.
> > > > > > > >  
> > > > > ...  
> > > > > > > > - Due to legal reasons, I need to preserve the authorship of
> > > > > > > >   each one responsbile for each patch. So, I need to start from
> > > > > > > >   the original patch from Kernel 4.4;  
> > > > > ...  
> > > > > > > I do acknowledge you need to preserve history and all -
> > > > > > > but this patchset is not easy to review.  
> > > > > > 
> > > > > > Why do we need to preserve history ? Adding relevant Signed-off-by and
> > > > > > Co-developed-by should be enough, shouldn't it ? Having a public branch
> > > > > > that contains the history is useful if anyone is interested, but I don't
> > > > > > think it's required in mainline.  
> > > > > 
> > > > > Yea. I concur with Laurent here. I'm not sure what legal reasoning you
> > > > > have on this but preserving the "absolute" history here is actively
> > > > > detrimental for review and understanding of the patch set.
> > > > > 
> > > > > Preserving Authorship, Signed-off-by lines and adding Co-developed-by
> > > > > lines should be sufficient to provide both atribution credit and DCO
> > > > > history.  
> > > > 
> > > > I'm not convinced that, from legal standpoint, folding things would
> > > > be enough. See, there are at least 3 legal systems involved here
> > > > among the different patch authors:
> > > > 
> > > >       - civil law;
> > > >       - common law;
> > > >       - customary law + common law.
> > > > 
> > > > Merging stuff altogether from different law systems can be problematic,
> > > > and trying to discuss this with experienced IP property lawyers will
> > > > for sure take a lot of time and efforts. I also bet that different
> > > > lawyers will have different opinions, because laws are subject to
> > > > interpretation. With that matter I'm not aware of any court rules
> > > > with regards to folded patches. So, it sounds to me that folding
> > > > patches is something that has yet to be proofed in courts around
> > > > the globe.
> > > > 
> > > > At least for US legal system, it sounds that the Country of
> > > > origin of a patch is relevant, as they have a concept of
> > > > "national technology" that can be subject to export regulations.
> > > > 
> > > > From my side, I really prefer to play safe and stay out of any such
> > > > legal discussions.  
> > > 
> > > Let's be serious for a moment. If you think there are legal issues in
> > > taking GPL-v2.0-only patches and squashing them while retaining
> > > authorship information through tags, the Linux kernel if *full* of that.
> > > You also routinely modify patches that you commit to the media subsystem
> > > to fix "small issues".
> > > 
> > > The country of origin argument makes no sense either, the kernel code
> > > base if full of code coming from pretty much all country on the planet.
> > > 
> > > Keeping the patches separate make this hard to review. Please squash
> > > them.  
> > 
> > I'm inclined to agree with Laurent here.
> > 
> > Patches submitted as GPL-v2 with DCO lines and author names/companies
> > should be fine to be squashed and rearranged,
> > as long as the DCO and Authorship is kept somewhere in the new patch
> > that is applied.
> > 
> > Review is more important here.
> 
> Sorry, but I can't agree that review is more important than to be able
> to properly indicate copyrights in a valid way at the legal systems that
> it would apply ;-)

Regardless of the "review-ability", our users distribute the Linux
Kernel as a whole, so who contributed which specific line of code is
already lost in a way. All we see in the distribution if a list of
copyright holder and licenses. In this context, the per patches
ownership have no legal implication. My two, non lawyer cents.

> 
> In any case, there's an easy way to make the code easy to review:
> I can write the patches against staging (where it is OK to submit
> preserving the history) and then add a final patch moving it out
> of staging.
> 
> You can then just review the last patch, as it will contain the
> entire code on it.
> 
> Another alternative, as I'm already doing with Sam, is for me to
> submit the folded code as a reply to 00/xx. You can then just 
> review the final code, without concerning about how the code reached
> there.
> 
> From review point of the view, this will be the same as reviewing
> a folded patch, but, from legal standpoint, the entire copyright
> chain will be preserved.
> 
> Thanks,
> Mauro