linux-kernel - Re: [RESEND][PATCH 1/2] dt-bindings: usb: add non-removable-ports hub property

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Date:   Tue, 28 Jan 2020 14:47:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Måns Rullgård <mans@...sr.com>
Cc:     Rob Herring <robh@...nel.org>, Mark Rutland <mark.rutland@....com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND][PATCH 1/2] dt-bindings: usb: add non-removable-ports
 hub property

On Mon, Jan 27, 2020 at 04:56:15PM +0000, Måns Rullgård wrote:
> Rob Herring <robh@...nel.org> writes:
> 
> > On Fri, Jan 24, 2020 at 03:25:03PM +0000, Mans Rullgard wrote:
> >> Add a non-removable-ports property that lists the hardwired downstream
> >> ports of a hub.  Although hubs can provide this information, they are
> >> not always configured correctly.  An alternate means of indicating this
> >> for built-in USB devices is thus useful.
> >> 
> >> Signed-off-by: Mans Rullgard <mans@...sr.com>
> >
> > I reviewed this already, but since you didn't add my reviewed-by, I'm 
> > looking at it again and having 2nd thoughts.
> >
> >> ---
> >>  Documentation/devicetree/bindings/usb/usb-device.txt | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >> 
> >> diff --git a/Documentation/devicetree/bindings/usb/usb-device.txt b/Documentation/devicetree/bindings/usb/usb-device.txt
> >> index 036be172b1ae..92d863cc96b6 100644
> >> --- a/Documentation/devicetree/bindings/usb/usb-device.txt
> >> +++ b/Documentation/devicetree/bindings/usb/usb-device.txt
> >> @@ -66,6 +66,10 @@ Required properties for host-controller nodes with device nodes:
> >>  - #size-cells: shall be 0
> >>  
> >>  
> >> +Optional properties for hub and host-controller nodes:
> >> +- non-removable-ports: list of hardwired downstream ports
> >
> > If you have a hardwired device and need to know that, doesn't that imply 
> > there's some other stuff you need to describe beyond what a standard USB 
> > device has. Such as a power supply that's not Vbus from the hub.
> 
> I suppose there could be, but there isn't in my actual situation.
> 
> > At a minimum, I think this should be a per port property.
> 
> That's what I suggested first.  Greg told me to do it like this instead.

I said that?  I do not remember discussing this at all, when did that
happen?

> > Though really, I think this should just be implied by describing the
> > device in DT. I'm not sure if there's a case for hotpluggable devices
> > described in DT.  Maybe with overlays.
> 
> That's also an option.  Greg, what do you think?

I have no idea, sorry, I'm totally lost here...

greg k-h

> 
> -- 
> Måns Rullgård