The .dts file I was working from was produced by decompiling the .dtb file and therefore didn’t have any comments in it. Do you have a link to the upstream .dts file with the comments? That might help me figure out more opportunities for power reduction.
edit: For anyone else looking for this, here are the relevant links:
http://git.toradex.com/cgit/linux-toradex.git/tree/arch/arm64/boot/dts/freescale/fsl-imx8qxp-colibri-eval-v3.dts?h=toradex_imx_4.9.123_imx8mm_ga-bring_up
http://git.toradex.com/cgit/linux-toradex.git/tree/arch/arm64/boot/dts/freescale/fsl-imx8dx.dtsi?h=toradex_imx_4.9.123_imx8mm_ga-bring_up