Change in coreboot[master]: mb/google/volteer/variants/drobit: Add TBT PCIE rp setting for drobit

[Wayne3 Wang (Code Review)]

Attention is currently required from: Hank Lin, Tim Wawrzynczak, Nick Vaccaro, Ken Lu, Zhuohao Lee.
Wayne3 Wang has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/50103 )

Change subject: mb/google/volteer/variants/drobit: Add TBT PCIE rp setting for drobit
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Patch Set 1:

(2 comments)

File src/mainboard/google/volteer/variants/drobit/overridetree.cb:

https://review.coreboot.org/c/coreboot/+/50103/comment/f03515a8_dc7f0916 
PS1, Line 63: 		device ref tbt_pcie_rp0 on end
            : 		device ref tbt_pcie_rp1 on end
> Adding the `probe` statement(s) would probably be safest, but if all drobit SKUs will have USB4 then […]

I try to add the "probe DB_USB USB4_GEN3" to tbt_pcie_rp0 and tbt_pcie_rp1. But the system hangs in recovery page that can be duplicated again.

Modify >>>
    device domain 0 on
    	device ref tbt_pcie_rp0 on 
+			probe DB_USB USB4_GEN3
    	end
    	device ref tbt_pcie_rp1 on 
+			probe DB_USB USB4_GEN3		
    	end
    		
    	device ref i2c0 on
Modify <<<

I check the all drobit SKUs that will have the design of USB4. Maybe we can keep the settings?

https://review.coreboot.org/c/coreboot/+/50103/comment/185172e6_04386632 
PS1, Line 63: 		device ref tbt_pcie_rp0 on end
            : 		device ref tbt_pcie_rp1 on end
> Adding the `probe` statement(s) would probably be safest, but if all drobit SKUs will have USB4 then […]

I try to add the "probe DB_USB USB4_GEN3" to tbt_pcie_rp0 and tbt_pcie_rp1. But the system hangs in recovery page that can be duplicated again.

Modify >>>
    device domain 0 on
    	device ref tbt_pcie_rp0 on 
+			probe DB_USB USB4_GEN3
    	end
    	device ref tbt_pcie_rp1 on 
+			probe DB_USB USB4_GEN3		
    	end
    		
    	device ref i2c0 on
Modify <<<

I check the all drobit SKUs that will have the design of USB4. Maybe we can keep the settings?