From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Blumenstingl Subject: Re: [RFC usb-next v5 1/3] dt-bindings: usb: add the documentation for USB root-hub Date: Thu, 12 Oct 2017 23:35:46 +0200 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alan Stern Cc: Arnd Bergmann , linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, gregkh , felipe.balbi-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, mathias.nyman-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, Rob Herring , DTML , Mark Rutland , "open list:ARM/Amlogic Meson SoC support" , Chunfeng Yun List-Id: devicetree@vger.kernel.org Hi Alan, On Thu, Oct 12, 2017 at 11:17 PM, Alan Stern wrote: > On Thu, 12 Oct 2017, Martin Blumenstingl wrote: > >> I haven't tested the described use-case. however, this patch is not >> supposed to change the binding for actual devices. >> USB device numbering starts at 1, while 0 is reserved for the root-hub >> (at least from what I know). > > Actually 1 is reserved for the root hub. External devices are numbered > starting from 2. (We can't use 0 for the root hub because, as you > said, USB device numbering starts at 1!) I just had a look at lsusb again: $ lsusb -t /: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M however, for the devicetree bindings the devices are supposed to use 1-31: [0] Alan: just to make sure I understood you correctly: do you agree with this patch? > Alan Stern > >> before this patch there was no way to >> describe the root-hub via .dts. this however is required for some >> platforms that need to set up a PHY for each port on the root-hub >> (Amlogic Meson GXL platform is one example: there are two ports >> enabled on dwc3's root-hub with 2x USB2 and 1x USB3 PHYs) - so this >> patch uses a similar binding as we already have (to describe the >> devices) to describe the root-hub >> >> >> Regards, >> Martin >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-usb" in >> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> > Regards, Martin [0] http://elixir.free-electrons.com/linux/v4.14-rc4/source/Documentation/devicetree/bindings/usb/usb-device.txt -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html