CPU constantly enters/exits C10 during opportunistic suspend

[crawfxrd]

• Model: TGL-U+
• BIOS version: system76/firmware-open@b22e8dee415b
• EC version: system76/ec@a3fb9e1c7721
• OS: Pop!_OS 22.04
• Kernel: 6.5.4-76060504-generic

On systems with FSP C10 reporting enabled, the CPU will constantly enter/exit C10 during opportunistic suspend. This behavior can be observed by a flickering power LED.

Steps to reproduce

• Lock the screen, allowing it to turn off
• Wait 1 minute, watching the power LED
• Wake and unlock the system
• Check C-state values: sudo cat /sys/kernel/debug/pmc_core/package_cstate_show

Expected behavior

• Power LED either remains solid, or blinks at normal interval
• Lower C-state values don't increase significantly

Actual behavior

• Power LED flickers on/off rapidly
• Lower C-state values increase as much as deeper C-state values

Additional info