On Fri, Sep 27, 2024 at 1:19 AM Marek Vasut <ma...@denx.de> wrote: > > On 9/27/24 12:53 AM, Lothar Rubusch wrote: > > On Thu, Sep 26, 2024 at 3:36 AM Marek Vasut <ma...@denx.de> wrote: > >> > >> On 9/26/24 12:49 AM, Lothar Rubusch wrote: > >> > >> Hi, > > [...] > >>> Shall I add the files to my DTS patches and ask for upstreaming of the > >>> handoff files into the kernel? > >> > >> Are the handoff files really used by Linux for anything , or do they > >> contain various clock/pinmux/DRAM settings only used by U-Boot ? If the > >> later, place them into U-Boot and include them from -u-boot.dtsi file. > > > > Similar to the other socfpga targets, the handoff files are just > > relevant to u-boot. So, I'll keep them in arch/arm/dts. > > Right > > > My particular situation then is as follows. The .dts file just > > includes several .dtsi files. I place this .dts file into > > arch/arm/dts. The first includes contain the "handoff setup". Then I > > include adjustments (.dtsi fragments) to the selected base-board and > > boot-mode. Both can vary that's why I really would prefer to allow > > for a Kconfig option on that, in contrary to provide a set of .dts > > files for all possible combinations. > > > > Example: > > $ cat ./arch/arm/dts/socfpga_arria10_mercury_aa1_pe1_sdmmc-u-boot.dts > > Upstream DT named this way into Linux: > > socfpga_arria10_mercury_aa1_pe1_sdmmc.dts > > And then in U-Boot, implement the extras which include whatever you > need, name the file: > > socfpga_arria10_mercury_aa1_pe1_sdmmc-u-boot.dtsi > > The U-Boot build system will combine the two DTs, the build system > should automatically append matching -u-boot.dtsi content to any .dts file. > > I am not sure if this also works if the .dts file is in dts/upstream/* > while the -u-boot.dtsi is in arch/*/dts/ , but there is now definitely a > use case for such a setup, it is probably a matter of tweaking the > Makefiles . > > > /dts-v1/; > > /* will be taken from /arch/arm/dts */ > > #include "socfpga_arria10_mercury_aa1_handoff.h" > > #include "socfpga_arria10-handoff.dtsi" > > #include "socfpga_arria10_handoff_u-boot.dtsi" > > > > /* will be taken from /dts/upstream */ > > #include > > "../../../dts/upstream/src/arm/intel/socfpga/socfpga_arria10_mercury_aa1.dtsi" > > #include > > "../../../dts/upstream/src/arm/intel/socfpga/socfpga_enclustra_mercury_bootmode_sdmmc.dtsi" > > #include > > "../../../dts/upstream/src/arm/intel/socfpga/socfpga_enclustra_mercury_pe1.dtsi" > > > > Ideally, now I like to have the first part as default device tree. > > DEFAULT_DEVICE_TREE=socfpga_arria10_mercury_aa1_pe1_sdmmc-u-boot.dts > > When doing so, I noticed I cannot enable CONFIG_OF_UPSTREAM anymore, > > the files in arch/arm/dts won't be found anymore. > > Then I have the issue how to access the generic .dtsi files used for > > boot-mode or base board. These files are identical to the kernel DT > > why I would prefer to use them from dts/upstream. Including them like > > ../../../../../... works, but... I think there must be a better way. > > Look at how the -u-boot.dtsi are automatically added on top of .dts > files, that might be a start. > > > Ideally I like to setup some Kconfig choice for base board selection > > and one for boot-mode. > > > 1.) In the documentation control.rst I read that the u-boot.dts is > > combined of several elements. Is there a way to take this base .dts, > > then add a base board .dtsi by Kconfig option, and similar a > > boot-mode? > > The -u-boot.dtsi is preprocessed by C preprocessor, just like all the > other DTs, so you can have a -u-boot.dtsi file which contains C > preprocessor conditional statements in it to conditionally include other > .dtsi files: > > #if IS_ENABLED(...) > #include ... > #else ... > ... > #endif
Going through the include list setup by the Makefile made me find my mistake. Currently I may use u-boot specific stuff in arch/arm/dts and include generic .dtsi fragments from dts/upstream. Note: I'm not setting CONFIG_OF_UPSTREAM since I'm using the regular include list which already contains dts/upstream/src/arm/intel. Is this ok? Or, shall I try a different approach, which involves having CONFIG_OF_UPSTREAM explicitely set in the defconfig? > > 3.) What would be the best possibility to have a u-boot.dts with > > handoff setup in arch/arm/dts and append .dtsi files from the general > > dts/upstream - in case are there other boards are doing something > > similar? > > See above, maybe some of it helps. Yes. This helped. I can set base-board and boot mode now by Kconfig option with a generic .dts file. Note, it may still take some time, since I'd like to test the stuff still a bit on hardware before submitting something to the list.
