Re: [PATCH] usb: xhci: Handle USB3 port events when there is one roothub

Semih Baskan <[email protected]> Mon, 3 Aug 2026 16:35:46 +0300
Newsgroups org.kernel.vger.linux-usb,org.kernel.vger.linux-kernel
Message-ID <CAAsRjRk5oGO+=YEHxdDBxNAVi8cdeP8hq38NPKNfVYq_DN-EPw@mail.gmail.com>
On 8/3/26 16:13, Mathias Nyman wrote:
> Is some other host controller (xHCI/EHCI) handling USB2 traffic in this
> Broadcom Northstar case?

Yes. The SoC has three separate host controllers, each with its own node
and its own driver instance:

  ehci-platform 18021000.usb: new USB bus registered, assigned bus number 1
  ohci-platform 18022000.usb: new USB bus registered, assigned bus number 2
  xhci-hcd 18023000.usb: new USB bus registered, assigned bus number 3
  xhci-hcd 18023000.usb: USB2 root hub has no ports

The USB2 pins of the physical connectors go to the EHCI and OHCI
controllers rather than to the xHC, so the connectors stay backwards
compatible and the xHC never sees that half of them:

  usb 1-1: new high-speed USB device number 2 using ehci-platform
  usb 1-2: new high-speed USB device number 5 using ehci-platform
  usb 3-1: new SuperSpeed USB device number 2 using xhci-hcd

Both EHCI root ports are in use there, one per connector.

The layout comes from bcm-ns.dtsi, so it is every Northstar board
(BCM4708, BCM4709, BCM47081, BCM47094), not just this router.

Thanks for picking it up.

Semih