On Thu, Sep 26, 2024 at 3:36 AM Marek Vasut marex@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.
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 /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. 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?
2.) Is there a way to enable CONFIG_OF_UPSTREAM and use explicit DTS from arch/arm/dts for the u-boot?
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?