Comment 20 for bug 1745646

The TPM (Trusted Platform Module) ACPI device isn't know by the v4.13 kernel. Support for it was introduced with commit 4cb586a18 in v4.14 so it should be supported by the 18.04 kernel once it is rebased to v4.15, and will eventually be available to 16.04 as the package: linux-image-lowlatency-hwe-16.04-edge.

git describe --contains 4cb586a18
v4.14-rc2~6^2~34

It's possible the TPM is active and not using power-saving modes when the system is shutdown since Linux v4.13 doesn't know how to manage it (but it'll have been enabled by the firmware at boot time). This could explain why Windows doesn't see the same issue if it's TMP driver puts the device to sleep.

I'll review the disassembled DSDT/SSDTs later and leave remarks if I notice anything else that could be the culprit.