Nasty console and xe driver interactions

[Dave Hansen <dave.hansen@intel.com>]

I've got a custom kernel that has CONFIG_DRM_XE=y. I moved a disk from
an old NUC to a new Panther Lake one, and from it being SATA-attached to
USB-attached.

The new system was hanging after GRUB:

	Loading Linux ...
	Loading initial ramdisk ...
	<nothing>

Turns out, the root cause of the boot hang was my USB adapter needing a
rootdelay=15. But it took me a couple of hours, and a USB debug cable to
figure it out. Why?

Because the xe driver was falling over itself and presumably sabotaging
the firmware framebuffer in the process:

> [    1.505387] xe 0000:00:02.0: vgaarb: deactivate vga console
> [    1.507298] xe 0000:00:02.0: [drm] Running in SR-IOV PF mode
> [    1.512831] xe 0000:00:02.0: [drm] Tile0: GT0: GuC firmware xe/ptl_guc_70.bin not found
> [    1.512873] xe 0000:00:02.0: [drm] Tile0: GT0: GuC firmware(s) can be downloaded from https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
> [    1.512881] xe 0000:00:02.0: [drm] *ERROR* Tile0: GT0: Failed to initialize uC (-ENOENT)
> [    1.512894] xe 0000:00:02.0: probe with driver xe failed with error -2

So instead of getting a nice message about my root disk problems, I just
got a hang after GRUB. Basically, missing XE firmware results in a
system which is undebuggable for normal humans*.

There seem to have been similar issues in the past:

> https://lore.kernel.org/lkml/20251229215906.3688205-1-zack.rusin@broadcom.com/

Any chance that could be looked at again? This was a pretty insidious
failure mode.

 * Normal humans don't have USB debug cables lying around