Hello myself K S Sagar I want to know complete device tree modification process for jetson TX2I carrier board searched many nvidia videos,websites,forums but i was unable to find the solution because so many files and so many folders are there even after changing the required hdmi,usb core dtsi files for my jetson tx2i carrier board i was unable to detect any kind of change in my usb and hdmi present in my board though i have converted my modified dtsi file to dtb and have flashed the kernel and before flashing for safe side i have also checked my modifications by converting back to dts file so in that dts file i was able to see my modifications but they were not reflected on my board after flashing the kernel I request you to please kindly help me out as iam new to this nvidia family.
I can’t answer specifics for a given board. This is some background which might help though.
There are actually two places a device tree might load from. On eMMC models (you did not specify, but this seems likely if working on a custom carrier board or third party carrier board) there is a partition with device tree. There is also a file in “/boot”, as named by the FDT key/value pair in “/boot/extlinux/extlinux.conf”. The file named via FDT normally takes precedence, and if it is there and can be read, then this would be what loads in preference to the partition (in SD card model dev kits this is in QSPI memory instead of an eMMC partition for the one not in “/boot” via FDT).
When flashing a device tree to a partition the content is first signed before putting it in place (in fact all non-rootfs partitions are signed). The default is to sign with a NULL key. A partition without a proper signature will be refused. If security fuses are burned (which don’t exist on SD card models…this is an “eMMC thing”). When fuses are burned the “/boot” content is refused and only signed partitions are accepted.
If the device tree edits are not being read, and you’ve verified this (e.g., via “/proc/device-tree”), then get a full serial console boot log and watch where the tree loads from. Consider whether you’ve put this in “/boot” with an FDT entry in extlinux.conf, versus with flashing it to a partition or QSPI. Check the log to see if this is honored.
This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.