I have a Jetson Orin NX 16 GB configured on a custom carrier board and acting as a PCIe root port. I am trying to disable PCIe spread spectrum clocking. I follow the procedure outlined on page 17 of “Jetson Orin NX Series and Jetson Orin Nano Series Tuning and Compliance Guide”. I apply the patch to the dtb file found at $TOP/boot/dtb, but when I verify the clock on a spectrum analyzer after rebooting the Orin NX, SSC appears to still be applied to the clock. The text of the dts file (SSC_disabled.txt (311.6 KB)) that I convert to the patched dtb file is attached here. I would appreciate any advice regarding how to disable SSC on the Orin NX 16 GB.
Please reference to below topic.
I tried implementing that patch referenced in the post you linked to, but on the “clk-id = <TEGRA234_CLK_PLLE>;” line in the dts file, the dtc command returns the error “Error: SSC_disabled.dts:5894.15-16 syntax error”.
I’ve read that forum post as well. I applied that patch, which explicitly specifies the clk-id, to the dtb file, but SSC clocking has not been disabled when I probe the clock on a spectrum analyzer. When I read bit 12 of the clock registers (How to check SSC clock status), they are all set to 0, which indicates that SSC is still enabled.
Then the next thing you should check is if you modify the correct file and if that file is flashed to the board.
There are multiple bpmp dtb in use and not sure if you really modify the correct one.
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