[M] Change in coreboot[main]: soc/intel/cmn/gfx: Fix GFX modeset issue with dual-display

[Subrata Banik (Code Review)]

Attention is currently required from: Eric Lai, Kapil Porwal, Nick Vaccaro, Nico Huber, Paz Zcharya.

Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/78691?usp=email )

Change subject: soc/intel/cmn/gfx: Fix GFX modeset issue with dual-display
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Patch Set 4:

(1 comment)

Patchset:

PS4:
> Sorry, I missed all the MBUS reviews. This looks like workarounds for using
> the FSP/GOP as it would otherwise be implemented as part of the gfx init.
> Have you considered to implement this in `drivers/intel/fsp/`?

Intel GFX team will eventually implement MBUS joining in proper sometime after Q2
24.
> The logic in get_external_display_status() looks suspiciously as it would
> only work for the default pipe allocation chosen by the GOP. The internal
> display is often but not always on PORT_A.

you are right, the current assumption is that eDP/internal display using pipe-A
> And PORT_A can also be used with
> any pipe (i.e. not always pipe A). If the intend is to only make it work
> with the GOP, please move the code.

SOC_INTEL_GFX_MBUS_JOIN kconfig is implementation specific for ChromeOS device and plan is to move it into GFX driver sooner.