Re: [PATCH v2] usb: gadget: udc: core: Offload usb_udc_vbus_handler processing

[Alan Stern]

On Fri, May 19, 2023 at 04:30:41AM +0000, Badhri Jagan Sridharan wrote:
> chipidea udc calls usb_udc_vbus_handler from udc_start gadget
> ops causing a deadlock. Avoid this by offloading usb_udc_vbus_handler
> processing.

Look, this is way overkill.

usb_udc_vbus_handler() has only two jobs to do: set udc->vbus and call 
usb_udc_connect_control().  Furthermore, it gets called from only two 
drivers: chipidea and max3420.

Why not have the callers set udc->vbus themselves and then call 
usb_gadget_{dis}connect() directly?  Then we could eliminate 
usb_udc_vbus_handler() entirely.  And the unnecessary calls -- the ones 
causing deadlocks -- from within udc_start() and udc_stop() handlers can 
be removed with no further consequence.

This approach simplifies and removes code.  Whereas your approach 
complicates and adds code for no good reason.

Alan Stern