On 10/20/2022 10:59 AM, Krzysztof Kozlowski wrote: > 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. Going through this thread, this seems to be the conclusion. Will all clock nodes to the DTS files. > > Just note, that even in proposed frequency->board DTS, it is still > possible to use the clock-fixed-factor. > > Thanks, Melody
