Photonicat 2 Debian image forces nvme_core.default_ps_max_latency_us=0, but public mainline bootscript does not

Hello Photonicat team,

I am testing NVMe power management on a Photonicat 2 running Debian.

On the shipping image, /boot/boot.scr contains:
nvme_core.default_ps_max_latency_us=0

As a result, APST is disabled at runtime:
nvme get-feature /dev/nvme0 -f 0x0c -H
-> APSTE: Disabled

However, your public mainline repository
photonicat/rockchip_rk3576_linux_mainline
contains scripts/photonicat2.bootscript without this parameter, and build-base.sh generates boot.scr from that script.

So I have a concrete mismatch between:
1) shipping Debian boot.scr
2) public mainline Photonicat2 bootscript

Questions:

1. Is nvme_core.default_ps_max_latency_us=0 intentionally forced in the shipping Debian image for compatibility?
2. Is APST expected to work on Photonicat 2 with the public mainline Debian image?
3. Does the M.2 NVMe slot support runtime PM / D3cold / RTD3 on current hardware + DT?
4. Which image / branch should be used to test NVMe low-power states correctly on Photonicat 2?

My current test SSD is Samsung 970 PRO.
I can also provide:

• /proc/cmdline
• nvme id-ctrl -H
• nvme get-feature -f 0x0c -H
• dmesg for the PCIe/NVMe probe path

Best regards,
Vladimir

Hello,
This kernel parameter is missing in github repo because the public repo is out dated. We will sync the repo ASAP.
This parameter is added for better compatibility, as we found some SSDs may not work properly without it. For the same reason, we set ASPM to performance mode in kernel configuration. If you want to test whether power saving mode works on your SSD, you can try to remove nvme_core.default_ps_max_latency_us=0 from boot script and set ASPM to power-save in kernel configuration.