[Public] > -----Original Message----- > From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > Sent: Wednesday, August 25, 2021 3:26 AM > To: Felipe Balbi <balbi@xxxxxxxxxx> > Cc: Shah, Nehal-bakulchandra <Nehal-bakulchandra.Shah@xxxxxxx>; > gregkh@xxxxxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; Liu, Kun <Kun.Liu2@xxxxxxx>; Deucher, > Alexander <Alexander.Deucher@xxxxxxx> > Subject: Re: [RESEND PATCH 2/2] usb: dwc3: pci add property to allow user > space role switch > > On Wed, Aug 25, 2021 at 10:01:05AM +0300, Heikki Krogerus wrote: > > On Wed, Aug 25, 2021 at 08:55:41AM +0300, Felipe Balbi wrote: > > > > > > Hi, > > > > > > Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@xxxxxxx> writes: > > > > > > > For AMD platform there is a requirement to enable user space role > > > > switch from host to device and device to host as customer platform > > > > is not completely capable of OTG i.e. with type C controller it > > > > does not have PD to support role switching. Hence, based ACPI/EC > > > > interrupt role switch is triggered by the usemode script running in > background. > > > usermode ? > > > > Couldn't you capture that ACPI/EC interrupt in kernel? > > > > > > Signed-off-by: Nehal Bakulchandra Shah > > > > <Nehal-Bakulchandra.shah@xxxxxxx> > > > > > > I'm okay with this, just wondering if we need to Document the > > > property somewhere. > > > > > > @Heikki, is there a place to document these private properties > > > that's not on DT binding document? > > > > The build-in properties are not documented separately. I've always > > tried to supply DT bindings for all new properties I've proposed. > > > > In this case though, do we need the new property at all? Why not just > > register a normal USB role switch on this platform? It can be either a > > dummy role switch that only passes the user space input to dwc3, or, > > perhaps ideally, it would also be a driver that captures that ACPI/EC > > event/notification and then passes the information from it to dwc3. > > Please ignore the above question. Sorry. Let me try again... > > The question is: why not just capture that ACPI/EC "interrupt" in kernel and > then just use that information to set the dwc3 role switch? > No extra properties needed. I'm not a USB expert, but I think the idea was to pop up a message asking the user what role they wanted when they plugged in USB cable? Then based on their input, the role could be changed. Alex
