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

From: Rob Herring
Date: Mon Jan 27 2020 - 10:35:10 EST


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@xxxxxxxxx>

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