Enable/Disable IME by CMOS option

[crawfxrd]

Replace the Kconfig option to disable IME with a CMOS option.

• KBL boards use me_cleaner, so don't set the option at all
• TGL boards default to enabled
• Other boards default to disabled

Value can be changed with nvramtool:

sudo nvramtool -w ime_state={Enable,Disable}

Changing state requires a global reset, so the next boot after enabling/disabling will power off the machine.

---

Tested on oryp6 with the following change, to always dump the ME state:

diff --git a/src/soc/intel/cannonlake/me.c b/src/soc/intel/cannonlake/me.c
index 7bbe1ae730..6b831dc11e 100644
--- a/src/soc/intel/cannonlake/me.c
+++ b/src/soc/intel/cannonlake/me.c
@@ -103,8 +103,8 @@ void dump_me_status(void *unused)
        union me_hfsts5 hfsts5;
        union me_hfsts6 hfsts6;
 
-       if (!is_cse_enabled())
-               return;
+       //if (!is_cse_enabled())
+       //      return;
 
        hfsts1.data = me_read_config32(PCI_ME_HFSTS1);
        hfsts2.data = me_read_config32(PCI_ME_HFSTS2);

Then checked cbmem console (cbmem -c) to see the current working state and current operating mode.

---

Concerns: This might break on TGL because the CMOS bit is currently 0 (Disable). At the least, this would mean no C10 residency on TGL-U. And since we haven't figured out the issue on gaze16, poweroff/suspend will break.

---

Resolves: system76/firmware-open#219
Resolves: system76/firmware-open#197

Upstream: CB:57541

[jacobgkau]

Concerns: This might break on TGL because the CMOS bit is currently 0 (Disable). At the least, this would mean no C10 residency on TGL-U. And since we haven't figured out the issue on gaze16, poweroff/suspend will break.

This does seem to prevent galp5 from suspending, if that's what a lack of C10 residency looks like. The power LED never blinks.

[crawfxrd]

The power LED never blinks.

Yes, CPU_C10_GATE# doesn't assert when the IME kernel is disabled, so the LED won't blink.

This should output 0:

cat /sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us

And then you should be able to see which states it's reaching with this:

sudo cat /sys/kernel/debug/pmc_core/package_cstate_show

[crawfxrd]

Could probably just use an inverted enum (0=Enabled, 1=Disabled) for TGL to preserve the behavior.

[crawfxrd]

I'll try to get some feedback from upstream before making an incompatible change downstream.