Implement DP-IN on TGL-H

Basically implementing _DSM function 20 on UUID "3e5b41c6-eb1d-4260-9d15-c71fbadae414"

This bug is filed for Intel escalation.

The real discussion can be found here: https://lore.kernel.org/intel-gfx/20220816025217.618181-1-kai.heng.feng@canonical.com/

@jani FYI

added feature: display/Other label

@khfeng can you attach i915_opregion and i915_vbt from the affected machine here?

Also I'd like to see what intel_reg read 0x1638A0 0x16E8A0 0x16F8A0 says both before and after calling the DSM.

i915_opregion

i915_vbt

Before:

                                    (0x001638a0): 0x00000010
                                    (0x0016e8a0): 0x00000010
                                    (0x0016f8a0): 0xffffffff

After:

                                    (0x001638a0): 0x00008090
                                    (0x0016e8a0): 0x00008010
                                    (0x0016f8a0): 0xffffffff

Looks slightly weird in that the FIA seems to report TC1,TC2,TC4 switched to DPin mode, but TC3 did not. VBT however only declares three ports TC1,TC2,TC3, no TC4. That would seem to imply that TC3 remains available for the iGPU even after the DSM call.

Do I remember correctly that you said that at least some of the external ports do not work at all without the DSM call?

Yes, some ports on Thunderbolt dock don’t work.

Some some ports on the dock work and others don't? That sounds a bit weird. Isn't there just one upstream thunderbolt link between the laptop and dock? So not sure why this would have some effect on some of the ports on the dock. Hmm. Though the VBT only has three DDI ports declared, so I guess on one of the type-c connectors we can only get a single DP tunnel going. I wonder what that means for the dock side... @ideak do you know how this thunderbolt stuff usually gets routed on the dock side?

Does the laptop have multiple type-c connectors? If so do they all behave the same way?

Looks like only TC1+TC2 are declared as TBT+DP type-C in VBT. TC3 is supposed to be a legacy port then I guess.

added platform: TGL label

@vsyrjala , one TBT link will use two fixed DDIs either TC1/2, TC3/4 or TC5/6 allocating each on-demand as something is plugged to the dock (possibly also making a port wired directly to a connector on the host unusable). Not sure if this clarifies something, looking at the above registers now.

Is there any plan to add this support? This is crucial for more monitors support via TBT dock.