On 20/10/2022 13:18, Stephan Gerhold wrote: >> No, it puts attention to the board designer that he needs to provide the >> clock in his design. >> >> We had such talks about other platforms, although I do not have any >> recent bookmarks. Something older: >> >> https://lore.kernel.org/all/3382034.5ADO0F7naY@wuerfel/ >> >> https://lore.kernel.org/linux-samsung-soc/53DAB0A6.9030700@xxxxxxxxx/ >> > > If I understand you correctly your argument for having the clock in the > board DTS instead of the SoC DTSI is: > > The SoC DTSI describes the components of the SoC, while the board DTS > describes the components of the board (built around the SoC). The clock > is part of the board (and not the SoC) and therefore belongs into the > board DTS and not the SoC DTSI. Having the SoC/board components clearly > separated ensures people writing new board DTS pay attention to > everything board-specific. > > Correct? This sounds reasonable to me. Yes. > > However, the main question of my previous mail was: Why do you > alternatively recommend to keep the clock defined in the SoC DTSI and to > just put the clock-frequency into the board DTS? This sounds like a > contradiction of the above to me: the clock is still (partially) > described as part of the SoC, even though it belongs to the board. The proposal is a trade-off, compromise between code duplication and above recommendation of splitting SoC <-> board. As you said, all boards will provide this clock, so it is reasonable to put some pieces of it in the SoC DTSI to avoid duplication. But the final piece - what clock is there exactly (model, frequency etc) should be put in board DTS to clarify that this comes with board. > Someone writing a board DTS should not just put attention to the > clock-frequency, but also if they have a single fixed-clock or > maybe some kind of clock-fixed-factor setup, as I wrote. True. If such setup is probably, then my recommendation would be to put entire clock to the board. Just note, that even in proposed frequency->board DTS, it is still possible to use the clock-fixed-factor. Best regards, Krzysztof
