Re: [Buildroot] Xilinx KV260 Support

[Neal Frager <nealf@xilinx.com>]

Hi Peter,

> Le 16 avr. 2022 à 22:15, Peter Korsgaard <peter@korsgaard.com> a écrit :
> 
> CAUTION: This message has originated from an External Source. Please use proper judgment and caution when opening attachments, clicking links, or responding to this email.
> 
> 
>>>>>> "Neal" == Neal Frager <nealf@xilinx.com> writes:
> 
>> Dear buildroot community,
>> I am working on adding a defconfig for the Xilinx KV260 Starter Kit.
>> It is a low cost zynqmp development kit showcasing the first Xilinx Kria K26 SOM module.
>> https://www.xilinx.com/products/som/kria/kv260-vision-starter-kit.html
> 
> Looks nice!
> 
>> I have managed to get buildroot up and running on the hardware, but I currently need to implement some manual steps.
> 
>> Here are the issues I need to solve.  Both are related to a device tree overlay.
> 
>> 1. Install the zynqmp-sck-kv-g-revB.dtbo to the output/images directory:
>> BR2_LINUX_KERNEL_INTREE_DTS_NAME="xilinx/zynqmp-sm-k26-revA xilinx/zynqmp-sck-kv-g-revB"
>> BR2_LINUX_KERNEL_DTB_OVERLAYS_SUPPORT=y
> 
>> I need the build system to install the zynqmp-sm-k26-revA.dtb and the
>> zynqmp-sck-kv-g-revB.dtbo files to the output/images directory.
>> I have tried the BR2_LINUX_KERNEL_DTB_OVERLAYS_SUPPORT option above, but I do not see how to get the zynqmp-sck-kv-g-revB.dtbo
>> Instead of the zynqmp-sck-kv-g-revB.dtb.
> 
> Aren't they equvalent? E.G. the only difference between a normal .dtb
> and a .dtbo is afaik that dtc is executed with the -@ argument, which is
> what BR2_LINUX_KERNEL_DTB_OVERLAYS_SUPPORT does.
> 
> 
>> 2. Apply the overlay to generate a system.dtb in the post-image.sh:
> 
>> I am currently using the following command to generate the system.dtb that I need for booting:
>> fdtoverlay -o output/images/system.dtb -i output/images/zynqmp-sm-k26-revA.dtb output/images/zynqmp-sck-kv-g-revB.dtbo
> 
>> Does anyone have a good idea for how I could implement this in a generic way in the post-image.sh script?
> 
> Why are you using device tree overlays in the first place if you want to
> merge it back at build time?
> 
> Looking at the DTS submission from Michal, it sounds like something
> (U-Boot?) should do the carrier board detection and apply the correct
> overlay at runtime?
> 
> https://lkml.org/lkml/2021/9/22/116
> 

Thank you for your feedback.  Yes, I confirm that this works for the Linux kernel.

Now I just need to find the correct solution for u-boot.

> --
> Bye, Peter Korsgaard

Best regards,
Neal Frager
AMD
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