[M] Change in coreboot[master]: soc/intel/common/block: Add Intel VGA early graphics support

[Jérémy Compostella (Code Review)]

Attention is currently required from: Bora Guvendik, Zhixing Ma, Anil Kumar K, Hannah Williams, Cliff Huang, Tarun Tuli, Nico Huber, Michał Żygowski, Subrata Banik, Paul Menzel, Arthur Heymans, Swift Geek (Sebastian Grzywna).

Jérémy Compostella has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/70299 )

Change subject: soc/intel/common/block: Add Intel VGA early graphics support
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Patch Set 26:

(4 comments)

File src/soc/intel/common/block/graphics/early_graphics.c:

https://review.coreboot.org/c/coreboot/+/70299/comment/5558e9b7_dfcc20f4 
PS23, Line 6: static bool initialized;
> don't need drop please

Required with your suggested implementation in the SoC specific code tree.

https://review.coreboot.org/c/coreboot/+/70299/comment/3b2e3c06_776a133e 
PS23, Line 21: 	initialized = !!ret;
             : 
             : 	return initialized;
> return !!ret

Ack

https://review.coreboot.org/c/coreboot/+/70299/comment/22da93ad_0a30b1e1 
PS23, Line 29: 
             : 	if (!initialized)
             : 		return;
> Got it.  Thanks for the explanation. […]

I kept as it is required with the implementation you have recommended in the SoC specific code tree.

https://review.coreboot.org/c/coreboot/+/70299/comment/4156c301_a1dc9c2f 
PS23, Line 32: 
             : 	/*
             : 	 * Graphics MMIO device configuration may have been corrupted since it
             : 	 * has been initialized. The execution of a binary block such as FSP may
             : 	 * indeed have reset the PCI BAR0 address of the graphic device.
             : 	 */
             : 	early_graphics_soc_device_init();
> > > > Use suggestion here: https://review.coreboot. […]

I re-used your quite interesting `m_cfg->GttMmAdr = CONFIG_GFX_GMA_DEFAULT_MMIO` suggestion in the SoC specific code tree.

Regarding the use of your temporary MMIO region instead of the use of the use of a range in the memory hole we need to re-visit in the light of Angel interesting suggestion (https://review.coreboot.org/c/coreboot/+/70276/15/src/drivers/intel/gma/Kcon...)

Does it make sense to re-use a SPI map region and to have to release it if we consider `CONFIG_GFX_GMA_DEFAULT_MMIO` reserved for graphics MMIO operation and that we make it clear to the coreboot resource allocator that this is reserved for this purpose ?