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

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Message-ID: <20200127153506.GA4589@bogus>
Date:   Mon, 27 Jan 2020 09:35:06 -0600
From:   Rob Herring <robh@...nel.org>
To:     Mans Rullgard <mans@...sr.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.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 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.

At a minimum, I think this should be a per port property. 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.

Rob