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[209.85.219.182]) by smtp.gmail.com with ESMTPSA id z126-20020a816584000000b0059b50f126fbsm2527313ywb.114.2023.11.20.11.18.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Nov 2023 11:18:55 -0800 (PST) Received: by mail-yb1-f182.google.com with SMTP id 3f1490d57ef6-d9a518d66a1so4334191276.0; Mon, 20 Nov 2023 11:18:54 -0800 (PST) X-Received: by 2002:a5b:f4a:0:b0:da0:c49a:5103 with SMTP id y10-20020a5b0f4a000000b00da0c49a5103mr7300082ybr.47.1700507934171; Mon, 20 Nov 2023 11:18:54 -0800 (PST) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20231120084044.23838-1-krzysztof.kozlowski@linaro.org> <19358871-009d-4498-9c13-90d5338b1e9f@amd.com> <76fa8f61-fe31-4040-a38d-cc05be3f4f17@linaro.org> In-Reply-To: <76fa8f61-fe31-4040-a38d-cc05be3f4f17@linaro.org> From: Geert Uytterhoeven Date: Mon, 20 Nov 2023 20:18:42 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2] docs: dt-bindings: add DTS Coding Style document To: Krzysztof Kozlowski Cc: Michal Simek , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Matthias Brugger , AngeloGioacchino Del Regno , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, Andrew Davis , Arnd Bergmann , Bjorn Andersson , Geert Uytterhoeven , Heiko Stuebner , Konrad Dybcio , Neil Armstrong , Nishanth Menon , Olof Johansson , linux-rockchip@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-arm-msm@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Krzysztof, On Mon, Nov 20, 2023 at 3:53=E2=80=AFPM Krzysztof Kozlowski 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 organizi= ng DTSI > >> +and DTS files into several files: > >> + > >> +1. DTSI with contents of the entire SoC (without nodes for hardware n= ot 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 s= ay 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... Gr{oetje,eeting}s, Geert --=20 Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k= .org In personal conversations with technical people, I call myself a hacker. Bu= t when I'm talking to journalists I just say "programmer" or something like t= hat. -- Linus Torvalds