Ok,

filename: driver/gpu/drm/i915/

In tree it W(alk) then type:
d -> the tree should move the the first item in the tree that starts with 'd' (this happens to be driver
/ -> as the item is a directory and is selected it will be opened
g -> the tree will goto 'gpio'
p -> the tree does not move
u -> the tree moves to 'gpu'
/ -> as above
i -> tree moves to 'i2c'
9 -> tree moves to 'i915'
open the 'i915' directory and that it.

(Obviously could continue and find a file)
Also, to make it compatible with tab completion, will accept as well as '' (and I guess '/') for path item selection.