[L] Change in coreboot[main]: mb/asrock: Add Z87 Extreme4 (Haswell)

[Angel Pons (Code Review)]

Attention is currently required from: Jan Philipp Groß, Keith Hui, Máté Kukri, Nicholas Chin.

Angel Pons has posted comments on this change by Jan Philipp Groß. ( https://review.coreboot.org/c/coreboot/+/84672?usp=email )

Change subject: mb/asrock: Add Z87 Extreme4 (Haswell)
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Patch Set 9: Code-Review+2

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/84672/comment/ca9d2d94_75894196?usp... :
PS9, Line 34: - Dr. Debug (POST display)
I think vendor firmware turns this off by switching the pin functions, done through a single bit in the Super I/O's global config.

https://review.coreboot.org/c/coreboot/+/84672/comment/94129203_31467e93?usp... :
PS9, Line 35: - Various LEDs (mostly cosmetical, one however indicates which flash
            :   chip is currently being booted from)
LED power is likely controlled by a Super I/O GPIO