Hi Jagan, On Sun, Feb 24, 2013 at 8:19 AM, Jagan Teki <jagannadh.t...@gmail.com> wrote: > Hi Simon, > > Thanks for your response, please find my below comments. > > On Sun, Feb 24, 2013 at 9:24 PM, Simon Glass <s...@chromium.org> wrote: >> Hi Jagan, >> >> On Thu, Feb 21, 2013 at 9:03 AM, Jagan Teki <jagannadh.t...@gmail.com> wrote: >>> Hi All, >>> >>> I am planning to use devicetree on u-boot. >>> I have an experience to work with devicetree on Linux. >>> >>> For u-boot, I have read doc from doc/README.fdt-control. >>> I see some dts usages on tegra boards. >>> >>> I have lot of confusions with the concept itself. >>> >>> Is Linux and u-boot devicetree concept and build system are same? >> >> I don't really understand this question sorry. U-Boot and Linux use >> the device tree mainly for run-time configuration of drivers, so that >> the same driver code can operate on different boards. > > I am some how confusing the fdt usage in u-boot. > Because when compared to Linux, u-boot fdt setup mandatory to require > the CONFIG_DEFAULT_DEVICE_TREE > on the config file [from your previous comments]. > > is this the only difference when compared to Linux i guess..is it? > Linux defconfig file does need to hot-code > the dts.
Yes - that is a difference. Linux provides a way to build .dts files but it is not mandatory. At present it is mandatory with U-Boot, and only one file is built. It can easily be ignored though. > >> >>> >>> Suppose I have 4 boards J1, J2, J3 & J4 on my soc "emb".of vendor "vast" >>> For this requirement I have >>> board/vast/dts/J1.dts >>> board/vast/dts/J2.dts >>> board/vast/dts/J3.dts >>> board/vast/dts/J4.dts >>> >>> include/configs/emb_common.h ==> single configuration of all SOC >>> needed definitions >>> like defconfig in Linux. >>> >>> do I need any more files? >> >> That's enough for the basics I think. > > Is dtsi file require to add it on arch folder along with above. If your architecture is not one of those already supported (like arm tegra/exynos and x86) then yes you need to add this file in arch/<arch>/dts. What architecture are you using? > >> >>> >>> In emb_common.h i am defining >>> CONFIG_OF_SEPARATE is it sufficient? >> >> And CONFIG_OF_CONTROL >> >>> >>> My plan is to build u-boot and then build the dtb with specific >>> board and then combine. >> >> That's fine, and is how we do things on Chromium also. U-Boot tries to >> build an FDT even with CONFIG_OF_SEPARATE, so you need to put a >> default device tree file in your emb_common.h file that it can find. >> But you can ignore it, and for flashing your boards just use >> u-boot.bin plus whatever .dtb you want to select. > > So I will add the fdt support and then build the u-boot. > Is there any separate u-boot build command to build dts file. > My plan is to combine both u-boot and dtb. You can run dtc yourself if you like - see Makefile/dts for how it is done there. Once you have the .dtb binary, the easiest thing is to add it to the end of u-boot.bin, as described in README.fdt-control. > > Thanks, > Jagan. > >> >>> >>> I saw that all tegra boards config files are defining >>> CONFIG_DEFAULT_DEVICE_TREE if ie. the case dts is a compile time >>> option right. >>> am i correct? >> >> Yes - see above. This is convenient for testing and development. >> >>> >>> Please let me know your inputs. >> >> Regards, >> Simon >> >>> >>> -- >>> Thanks, >>> Jagan. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
