[coreboot-gerrit] Change in coreboot[master]: soc/intel/{skl,cnl,dnv,xeon_sp}: disable PM ACPI timer if chosen

[Michael Niewöhner (Code Review)]

Attention is currently required from:  Felix Singer, Furquan Shaikh, Mariusz Szafrański, Jonathan Zhang, Paul Menzel, Subrata Banik, Arthur Heymans, Patrick Rudolph, Lance Zhao, Nico Huber, Anjaneya "Reddy" Chagam, Johnny Lin, Tim Wawrzynczak, Christian Walter, Suresh Bellampalli, Vanessa Eusebio, Michal Motyl, Tim Chu.
Michael Niewöhner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57932 )

Change subject: soc/intel/{skl,cnl,dnv,xeon_sp}: disable PM ACPI timer if chosen
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Patch Set 33:

(1 comment)

File src/soc/intel/xeon_sp/pmc.c:

https://review.coreboot.org/c/coreboot/+/57932/comment/1081c367_49425d8d 
PS33, Line 60: Disabling ACPI PM timer also switches off TCO.
> AIUI, it's hardware behavior, one timer depends on the other. If it […]

Nico is right, this is hardware behaviour. The TCO timer uses the PM timer (= ACPI timer) as clock source. When stopping this clock source, both timers stop.

I know, the naming of the UPDs is more than confusing... the TCO timer is not stopped by any UPD, though.