Re: [PATCH] drvier: usb: dwc3: Fix runtime PM trying to activate child device xxx.dwc3 but parent is not active

Alan Stern
2025-08-30T00:46:25Z

On Fri, Aug 29, 2025 at 08:13:07PM +0000, Thinh Nguyen wrote:
> ..shouldn't the PM core know that A was runtime suspended to not skip
> ->resume? (sorry I'm not an expert in the PM core, genuine question
> here).

This doesn't answer your question directly, but I would like to add some
background.

There are subsystems/drivers that do want to resume their devices during
system resume, even if the devices were in runtime suspend originally.
At a minimum, the PM core doesn't want to take this choice away from
them.

In fact, the USB subsystem was designed to run that way back when
support for runtime PM was first added, and it hasn't been changed since
-- although maybe it should be. There are explicit mechanisms for
telling the PM core that a device should be skipped during system
resume; we could use them.

Regardless, I don't recall any discussions of the particular situation
in this thread ever taking place.

Alan Stern