From: "Deucher, Alexander" <Alexander.Deucher@amd.com>
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Felipe Balbi <balbi@kernel.org>
Cc: "Shah, Nehal-bakulchandra" <Nehal-bakulchandra.Shah@amd.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Liu, Kun" <Kun.Liu2@amd.com>
Subject: RE: [RESEND PATCH 2/2] usb: dwc3: pci add property to allow user space role switch
Date: Wed, 25 Aug 2021 13:50:48 +0000 [thread overview]
Message-ID: <BL1PR12MB51443C94208DDE0AEBCB91A6F7C69@BL1PR12MB5144.namprd12.prod.outlook.com> (raw)
In-Reply-To: <YSXwkKJ53d/uwnhy@kuha.fi.intel.com>
[Public]
> -----Original Message-----
> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Sent: Wednesday, August 25, 2021 3:26 AM
> To: Felipe Balbi <balbi@kernel.org>
> Cc: Shah, Nehal-bakulchandra <Nehal-bakulchandra.Shah@amd.com>;
> gregkh@linuxfoundation.org; linux-usb@vger.kernel.org; linux-
> kernel@vger.kernel.org; Liu, Kun <Kun.Liu2@amd.com>; Deucher,
> Alexander <Alexander.Deucher@amd.com>
> 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@amd.com> 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@amd.com>
> > >
> > > 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
next prev parent reply other threads:[~2021-08-25 13:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 19:23 [RESEND PATCH 2/2] usb: dwc3: pci add property to allow user space role switch Nehal Bakulchandra Shah
2021-08-25 5:55 ` Felipe Balbi
2021-08-25 7:01 ` Heikki Krogerus
2021-08-25 7:26 ` Heikki Krogerus
2021-08-25 13:50 ` Deucher, Alexander [this message]
2021-08-26 14:06 ` Heikki Krogerus
2021-09-02 12:45 ` Shah, Nehal-bakulchandra
2021-09-09 12:55 ` Heikki Krogerus
2021-08-25 7:43 ` Felipe Balbi
2021-08-26 11:13 ` Greg KH
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