Hi, On Tue, Dec 12, 2023 at 4:52 PM Andrew Davis <a...@ti.com> wrote: > On 12/12/23 8:05 AM, Simon Glass wrote: > > The devicetree files for a board can be quite large, perhaps around > > 60KB. To boot on any supported board, many of them need to be > > provided, typically hundreds. > > > > All boards for a particular SoC share common parts. It would be > > helpful to use overlays for common pieces, to reduce the overall size. > > > > For this to save much size we would need to have the SoC split > from each board that uses it. We don't have that in DT today. > There are some efforts in progress to help on this but until > then we will not get much here.
Indeed. E.g. The Kingfisher board[1] is an extension for (various) ULCB boards[2], but we cannot use an overlay for the former, as the combinations need to have different top-level compatible (and model) values. Hence currently we use a .dtsi file and lots of extra .dts files[3]. The other issue is the need for parameterization, due to slight differences in pins/signals on various base boards, or because the same connector is present multiple times (e.g. for multi-camera setups[4][5]). [1] arch/arm64/boot/dts/renesas/ulcb-kf.dtsi [2] arch/arm64/boot/dts/renesas/*-ulcb.dts [3] arch/arm64/boot/dts/renesas/*-ulcb-kf.dts [4] arch/arm/boot/dts/renesas/r8a7742-iwg21d-q7-dbcm-ov5640-single.dtsi [5] arch/arm/boot/dts/renesas/r8a7742-iwg21d-q7-dbcm-ov7725-single.dtsi Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds