On Fri, Mar 26, 2021 at 03:19:00PM -0400, Jim Quinlan wrote:

Control of EP regulators by the RC is needed because of the chicken-and-egg
situation: although the regulator is "owned" by the EP and would be best
handled on its driver, the EP cannot be discovered and probed unless its
regulator is already turned on.

Ideally the driver core would have a way for buses to register devices
pre physical enumeration and give drivers a callback that could be used
to do whatever is needed to trigger enumeration, letting the bus then
match newly physically enumerated devices with the software enumerated
struct devices.  Soundwire has something in this area for a bus level
solution.