Re: [PATCH v2] docs: dt-bindings: add DTS Coding Style document

[Michal Simek]

On 11/20/23 20:31, Krzysztof Kozlowski wrote:
> On 20/11/2023 20:18, Geert Uytterhoeven wrote:
> > Hi Krzysztof,
> >
> > On Mon, Nov 20, 2023 at 3:53 PM Krzysztof Kozlowski
> > <krzysztof.kozlowski@xxxxxxxxxx> wrote:
> > > On 20/11/2023 15:01, Michal Simek wrote:> >
> > > > On 11/20/23 09:40, Krzysztof Kozlowski wrote:
> > > > > Document preferred coding style for Devicetree sources (DTS and DTSI),
> > > > > to bring consistency among all (sub)architectures and ease in reviews.
> >
> > > > > +Organizing DTSI and DTS
> > > > > +-----------------------
> > > > > +
> > > > > +The DTSI and DTS files should be organized in a way representing the common
> > > > > +(and re-usable) parts of the hardware.  Typically this means organizing DTSI
> > > > > +and DTS files into several files:
> > > > > +
> > > > > +1. DTSI with contents of the entire SoC (without nodes for hardware not present
> > > > > +   on the SoC).
> > > > > +2. If applicable: DTSI with common or re-usable parts of the hardware (e.g.
> > > > > +   entire System-on-Module).
> > > >
> > > > DTS/DTSI - SOMs can actually run as they are that's why it is fair to say that
> > > > there doesn't need to be DTS representing the board.
> > >
> > > I have never seen a SoM which can run without elaborate hardware-hacking
> > > (e.g. connecting multiple wires to the SoM pins). The definition of the
> > > SoM is that it is a module. Module can be re-used, just like SoC.
> >
> > /me looks at his board farm...
> >
> > The Renesas White-Hawk CPU board can be used standalone, and has a
> > separate power input connector for this operation mode.  As it has RAM,
> > Ethernet, serial console, eMMC, and even mini-DP, it can serve useful
> > purposes on its own.
> > I agree it's not a super-good example, as the board is not really a
> > "SoM", and we currently don't have r8a779g0-white-hawk-cpu.dts, only
> > r8a779g0-white-hawk-cpu.dtsi.
> >
> > The RZ/A2M CPU Board is a real SoM, which can be powered over USB.
> > It has less standard connectors (microSD, USB, MIPI CSI-2), but still
> > sufficient features to be usable on its own.
> > Again, we're doing a bad job, as we only have a DTS for the full eval
> > board (r7s9210-rza2mevb.dts).
> >
> > I guess there are (many) other examples...
>
> OK, I never had such in my hands. Anyway, the SoM which can run
> standalone  has a meaning of a board, so how exactly you want to
> rephrase the paragraph?

What about?

2. If applicable: DTSI with common or re-usable parts of the hardware (e.g.
entire System-on-Module). DTS if runs standalone.

Thanks,
Michal