Maxim Polyakov has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/32044 )
Change subject: soc/intel/skylake: Update GFX devtree options ......................................................................
Patch Set 8:
Patch Set 7: Code-Review-1
IMO, this patch does too much at once to keep track of everything...
Open questions:
- Why change the PrimaryDisplay setting of h110m?
- Why would we ever set `PrimaryDisplay = Display_Auto` together with `SkipExtGfxScan`?
- If I didn't miss it, the `SkipExtGfxScan` UPD wasn't set before? So this change changes all boards without mentioning it?
- What does `SkipExtGfxScan` do anyway?
4) "What does SkipExtGfxScan do anyway?" - If this parameter = 1, then FSP will not scan existing external graphics cards on the pci bus.
At the same time, it is worth noting that some payloads can ignore these parameters. For example, tianocore uses an NVIDIA GPU even if SkipExtGfxScan is set to 1. I think this happens because tianocore initializes the GPU again, it executes the code and registers the handlers from the uefi-rom-extension. In this case, the bootsplash first appears on the display connected to iGFX, and then the linux boot information is displayed on the NVIDIA GPU Display.
seabios uses the configuration from coreboot and doesn`t override the displays.