Re: [PATCH v3] arm64: dts: qcom: apq8016-sbc-d3: Add Qualcomm APQ8016 SBC + D3Camera mezzanine

From: Robert Foss <robert.foss@linaro.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>,
	linux-arm-msm@vger.kernel.org,
	devicetree <devicetree@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Nicolas Dechesne <nicolas.dechesne@linaro.org>
Subject: Re: [PATCH v3] arm64: dts: qcom: apq8016-sbc-d3: Add Qualcomm APQ8016 SBC + D3Camera mezzanine
Date: Mon, 25 May 2020 10:35:50 +0200	[thread overview]
Message-ID: <CAG3jFytUvfwFKvysKpRhrRRAotMv-epQZA3zq8DG0QdrQMpfyg@mail.gmail.com> (raw)
In-Reply-To: <20200519232442.GE2165@builder.lan>

Hi Bjorn,

Thanks for the review. I'll incorporate the changes if we decide to
that this DT should live upstream.

On Wed, 20 May 2020 at 01:26, Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On Tue 19 May 03:22 PDT 2020, Manivannan Sadhasivam wrote:
>
> > Hi Robert,
> >
> > On Mon, May 18, 2020 at 10:21:29AM +0200, Robert Foss wrote:
> > > Add device treee support for the Qualcomm APQ8016 SBC, otherwise known as
> > > the Dragonboard 410c with the D3Camera mezzanine expansion board.
> > >
> > > The D3Camera mezzanine ships in a kit with a OmniVision 5640 sensor module,
> > > which is what this DT targets.
> > >
> >
> > What is the motivation behind adding this new dts? We have been using the
> > userspace tool [1] for applying this as an overlay for some time. But if we
> > start adding dts for mezzanines then for sure we'll end up with some good
> > numbers which will flood arch/{..}/qcom directory.
> >
> > I could understand that one of the motivation is to provide nice user experience
> > to users but that's also taken care by the dt-update tool IMO.
> >
>
> The motivation for posting this was to provoke a response like yours.
>
> I knew about [1], but not that it included the overlays. I'm okay with
> using overlays and the dt-update tool. But I would have preferred that
> the dts files didn't live out of tree, given that this approach breaks
> if I change the name of a node you depend on upstream.

I wasn't aware of the dt-update tool, and it seems pretty neat.
However, a thought I had is that using it to enable a dt-node or a
board variant is not very different from applying a patch the the
upstream tree. The work it takes to do it is about the same, and the
maintenance burden of using a patch is about the same as using
dt-tool.

> > [1] https://github.com/96boards/dt-update