Hello, (please keep the barebox mailing list in CC) On 1/27/20 3:02 PM, gianluca wrote: > On 01/24/2020 05:13 PM, Ahmad Fatoum wrote: >> Hello, >> >> On 1/24/20 4:32 PM, gianluca wrote: >>> I was wondering if the device tree from (latest) Linux Kernel can be used when building Barebox 2020.01.0 for iMX6 compatible custom board. >>> For sure the include path and other stuff are quite different (kernel and barebox), so I am pretty sure it will fail to build with some sort of "foreign" device-tree. >> >> barebox already regularly imports Linux's device tree directories into its dts/ directory. >> v2020.01.0 contains the v5.4-rc7 state. >> > > Good to hear... > >> Another issue, will be the drivers to have full access from Barebox-Point-Of-View. If the device-tree properties and compatible strings are quite different, Barebox will fail to activating/probing/using the internal driver. >> >> barebox driver compatibles should be aligned with the kernel's. >> If a barebox driver lacks handling for a property, the driver can be extended. >> >>> So I am asking: >>> There is a "official" way to manage those differencies? >> >> I recently added a short section about this in the Documentation >> (https://barebox.org/doc/latest/devicetree/index.html): >> >> "For supporting architectures, barebox device trees are located in arch/$ARCH/dts. >> Usually the barebox board.dts imports the upstream device tree under dts/src/$ARCH >> with #include "$ARCH/board.dts" and then extends it with barebox-specifics like >> Barebox state, environment or boot-time device configuration." >> >> Take a look at arch/arm/dts/imx6q-marsboard.dts to see how that looks in practice. >> The kernel device tree is reused as is and extended slightly for barebox use. > > So, basically the device-tree stuff in Barebox are different from the Linux kernel one only for the #include path? The barebox device trees for ARM are in arch/arm/dts. Best practice is that these device trees include the upstream device tree with just the barebox changes custom. > The biggest issue I've found here, is the compatibility of the device-tree nodes for my board referring the standard imx6 board. For example: > > &uart3 { > status = "okay"; > }; > > is good as you are using the standard pinout for uart3. > > But, if I am using a different pinout layout for the same device, this is not working at all. > > Maybe I have to find the device-node parent, then looking for its configuration, and if it fits my needs, ok I will use it. > > Otherwise I have to redefine a new configuration node: > > uart3 { > pinctrl = .... > interrupts = ... > }; > > But this does not work. uart3 is already defined into the parent node of imx6q.dtsi. > > In that case I need to redefine a new name: > > my_uart3 { > pinctrl = ... > interrupts = ... > }; > > &my_uart3 { > status = "okay"; > }; > > I hope you understand what I am trying to tell you. You don't need to do this, you can just write &uart3 { pinctrl = ...; status = "okay"; }; These properties will override the properties from earlier in the preprocessed file. Cheers Ahmad > > Best regards, > Gianluca -- Pengutronix e.K. | | Steuerwalder Str. 21 | https://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
