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radFITimage
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Registered: ‎02-16-2021

Apply change to Device Tree that will only be applied to U-Boot

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We currently have a unified Petalinux project that is cleanly building and boot.

We have a shared MDIO bus for two GEMs based on my research this is not supported in U-Boot Ref: https://forums.xilinx.com/t5/Embedded-Linux/Two-separated-device-trees-for-u-boot-and-petalinux-kernel/td-p/1024741

The ideal way to fix this is to DTC with one GEM enabled, then append the status  = "ok" just prior recompiling and handing off to the kernel.

I am unsure of the hooks that could be used to execute this. Any help would be great.

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radFITimage
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Registered: ‎02-16-2021

Thanks for information.

I have not tested with both Phys on the MDIO but I was able to use AR 72620 to get a ping on a single ethernet channel. I used dt with GEM1 disabled using SGMII.  I tried to locate the u-boot configuration you mentioned but didn't see it 2019.2. I am going to try re-enabling the second GEM/Phy and see if this resolves the issue.

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stephenm
Xilinx Employee
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Registered: ‎09-12-2007

I can check the support for the multi phy uboot support.

However, in the mean time. you can look at the uboot fdt utility. This will allow you to change the DTB before you boot the kernel.

 

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radFITimage
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Registered: ‎02-16-2021

I also noticed AR72620: https://www.xilinx.com/support/answers/72620.html and am testing this. Note both Phys work in Linux.

The device tree for U-boot is embedded in the FSBL/UBOOT Boot.bin with another one loaded into the FIT so there are isolated .dtb.  The question is more how to do it in petalinux-yocto flow.

 

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stephenm
Xilinx Employee
Xilinx Employee
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Registered: ‎09-12-2007

Separate DTB is supported in Petalinux, in petalinux-config:

uboot_dtb.PNG

https://www.xilinx.com/support/documentation/sw_manuals/xilinx2020_2/ug1144-petalinux-tools-reference-guide.pdf

Not sure about Yocto

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radFITimage
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Registered: ‎02-16-2021

Thanks for information.

I have not tested with both Phys on the MDIO but I was able to use AR 72620 to get a ping on a single ethernet channel. I used dt with GEM1 disabled using SGMII.  I tried to locate the u-boot configuration you mentioned but didn't see it 2019.2. I am going to try re-enabling the second GEM/Phy and see if this resolves the issue.

View solution in original post

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