For tracking backport progress. Patches needed:
PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily
PM / sleep: Update device PM documentation to cover direct_complete
device core: add device_is_bound()
PM / Domains: add setter for dev.pm_domain
USB / PM: Allow USB devices to remain runtime-suspended when sleeping
CHROMIUM: scsi: allow scsi devices to use direct complete
PM / sleep: try to runtime suspend for direct complete (needs fix based on upstream feedback)
PCI / PM: Avoid resuming PCI devices during system suspend
PCI / PM: Avoid resuming more devices during system suspend
PM / PCI / ACPI: Kick devices that might have been reset by firmware

Dependencies:
PM / sleep: Two flags for async suspend_noirq and suspend_late
PM / sleep: Asynchronous threads for resume_noirq
PM / sleep: Asynchronous threads for resume_early
PM / sleep: Asynchronous threads for suspend_noirq
PM / sleep: Refine diagnostic messages in enter_state()
PM / sleep: Add flags to indicate platform firmware involvement
PM / sleep: Drop pm_request_idle() from pm_generic_complete()

Maybe merge:
PM / sleep: Go direct_complete if driver has no callbacks (had issues on 3.18 with audio)

All of these may not be required, and there might be more dependencies needed that I haven't found yet.