[coreboot-gerrit] Change in coreboot[master]: drivers/intel/gma: Support IGD Opregion 2.1

[Meera Ravindranath (Code Review)]

Attention is currently required from: Nico Huber, Krishna Prabhakaran, Furquan Shaikh, Maulik V Vaghela, Selma Bensaid, Subrata Banik, Patrick Rudolph.
Meera Ravindranath has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/52758 )

Change subject: drivers/intel/gma: Support IGD Opregion 2.1
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Patch Set 14:

(2 comments)

File src/drivers/intel/gma/opregion.c:

https://review.coreboot.org/c/coreboot/+/52758/comment/7f3f5fab_27215da5 
PS13, Line 277:
> knowing that we have only 2_1 and 2_0. […]

Agreed. Done

https://review.coreboot.org/c/coreboot/+/52758/comment/1d0a32e5_9fd71a2c 
PS13, Line 358:  Left-shift version field to accommodate Intel Windows driver quirk
              : 	 * when not using a VBIOS.
> I think this comment can be dropped? The left shift is required as per 2.0+ spec.

I think the left shift is always needed. Earlier the Major version was shifted by 24.
As now we have a minor version too, it needs a shift by 16.

Bits [31:24] - Major Version Number
BCD Integer representing the major version of the OpRegion
Bits [23:16] - Minor Version Number
BCD Integer representing the minor version of the OpRegion