Hibernation/Suspend-to-disk in Jetson TX2. Is it possible?

Our company bought few Jetson TX2 dev kit and System hibernation is a must feature for us and we are at its planning stage.

I could find, arm64 hibernation patches in mailing lists. I am trying to port them to TX2.

But I feel some statements in TRM are not giving a confidence for my planning stage.

After reading Parker’s TRM, I understood the following.

1] Parker SoC uses certain power management firmwares(bpmp.bin).

2] It has some AON cluster which does some Power management stuffs for Parker.

3] BPMP, a dedicated boot and power management core is present on which bpmp.bin is running.

4] There is a Power management controller (PMC) which does some system context save before LP0 entry.

5] PMC also assert reset signal to all modules in the SoC during LP0 exit.

6] Along with this ARMv PSCI is also present.
I think, system is giving a secure call to PSCI for suspend-to-mem. And then PSCI, PMC, and PM firmware plays some crucial role. This role is unknown to me.

7] Also some pads states are retained even during LP0(suspend-to-ram or deep sleep state) state.

8] Also in the kernel platform code I could not find much saving and restoring of context of different IPs.

9] I could not find who is saving and restoring CCPLEX’s GIC context.
Also there are other GIC present for other engine cores as well.

8] PMIC is connected to BPMP’s i2c contoller.
This means while wakeup BPMP fw does something on PMIC configuration. Is it?

9] From L4T 27.1 linux kernel soruce, I could not understand who is currently restoring PLLs, other CAR registers, and power to different IPs in SoC during a suspend-to-mem(entry and exit from LP0).

10] Separate GPMC is present for saving context of GPU. These saving are done on that IP’s internal RAM and not to external DRAM.

11] Microcode carveout reservation of 128MB is present in DRAM for Denver CPUs and it cannot be accessed by CCPLEX.

I think system hibernation has to anyways save all such information to Disk and restore them while resuming. And this I can do it from linux kernel only as other parts are black box for me.

As I could not get much information about all these important save/restore of context of different IPs in SoC from nvidia’s linux 4.4, and crucial role played by PM firmwares, I am little worried to move forward as I know arm64 hibernation patches along will not help me.

Any suggestion from Nvidia would be really help full in this situation.
I am using L4T 27.1 for my BSP work.

Thanks,
Chivas.

@chivas_regal
We didn’t implement/verify this feature. However as my understand the power state and boot process of hibernation is the same with reset only the OS/APP state is different. You should ignore the power manager to try it.

any update about this topic?