On 21/11/2023 08:33, Michal Simek wrote: > > > 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. OK, but then it's duplicating the option 3. It also suggests that SoM should be a DTS, which is not what we want for such case. Such SoMs must have DTSI+DTS. Best regards, Krzysztof
