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

[Furquan Shaikh (Code Review)]

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

Change subject: drivers/intel/gma: Support IGD Opregion 2.1
......................................................................

Patch Set 14:

(5 comments)

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

https://review.coreboot.org/c/coreboot/+/52758/comment/6e0bc9f0_5a2ee306 
PS14, Line 20: u32	version;
I think we should update this to match how kernel (and the spec) defines this:

(https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/i915/display/...)

```
    struct {
    	u8 rsvd;
    	u8 revision;
    	u8 minor;
    	u8 major;
    }  __packed over;
```

https://review.coreboot.org/c/coreboot/+/52758/comment/55b5cb48_757468a9 
PS14, Line 145: Physical address of Raw VBT data
This needs update.

(https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/i915/display/...)

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

https://review.coreboot.org/c/coreboot/+/52758/comment/03016642_bb98db26 
PS14, Line 271: if (CONFIG(INTEL_GMA_OPREGION_2_1))
              : 		return 0x201;
              : 
              : 	return 0x200;
Sorry about the back n forth on this. I think this function should set the individual fields of `over` as commented here https://review.coreboot.org/c/coreboot/+/52758/14/src/drivers/intel/gma/opre...:

```
static void opregion_set_version(igd_opregion_t *opregion)
{
     opregion->over.major = 2;
     opregion->over.reserved = 0;
     opregion->over.revision = 0;

if (CONFIG(INTEL_GMA_OPREGION_2_1))
          opregion->over.minor = 1;
     else
          opregion->over.minor = 0;
}
```

https://review.coreboot.org/c/coreboot/+/52758/comment/fb28d39b_c28a8ca3 
PS14, Line 288: 2.0
2.1

(https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/i915/display/...)

https://review.coreboot.org/c/coreboot/+/52758/comment/a476d827_e68d457b 
PS14, Line 290: CONFIG(INTEL_GMA_OPREGION_2_1)
With the above change to set version, you don't need to check the config again here. Instead we should check major/minor version:

```
if (opregion->over.major >= 2 && opregion->over.minor >= 1)
```

This will ensure that we don't have to modify this function again when we add support for a new version (which hasn't changed the meaning of rvda).