From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: "Tomasz Moń" <tomasz.mon@nordicsemi.no>
Cc: Andreas Noever <andreas.noever@gmail.com>,
Michael Jamet <michael.jamet@intel.com>,
Yehezkel Bernat <YehezkelShB@gmail.com>,
linux-usb@vger.kernel.org
Subject: Re: USB 2.0 host controller for Thunderbolt 4
Date: Tue, 23 May 2023 12:01:32 +0300 [thread overview]
Message-ID: <20230523090132.GO45886@black.fi.intel.com> (raw)
In-Reply-To: <bd807b391dec726401e36a25f8c8987571d771be.camel@nordicsemi.no>
Hi,
On Tue, May 23, 2023 at 10:53:17AM +0200, Tomasz Moń wrote:
> Hello,
>
> Dell Latitude 5330 with 12th Gen Intel(R) Core(TM) i7-1265U contains
> following PCI devices:
> * 8086:461e - Alder Lake-P Thunderbolt 4 USB Controller
> * 8086:51ed - Alder Lake PCH USB 3.2 xHCI Host Controller
>
> Thunderbolt 4 USB Controller initializes first and therefore following
> usb host controllers are registered:
> * usb1 - USB 2.0 High-Speed
> * usb2 - USB 3.2 Enhanced SuperSpeed
> * usb3 - USB 2.0 High-Speed
> * usb4 - USB 3.1 Enhanced SuperSpeed
>
> When I connect SuperSpeed device directly to the Dell Latitude, it ends
> up on usb4. Low/Full/High-Speed devices end up on usb3 as expected.
>
> When I connect Thunderbolt 3 dock, two new host controllers show up:
> * usb5 - USB 2.0 High-Speed
> * usb6 - USB 3.0 SuperSpeed
>
> Devices connected through Thunderbolt 3 dock end up on expected host
> controllers, i.e. Low/Full/High-Speed devices connect to usb5 and
> SuperSpeed devices end up on usb6.
>
> Is Thunderbolt 3 essentially tunnelling the USB 2.0 traffic (by
> tunnelling PCIe xHCI host controller traffic) on the superspeed
> differential pairs (operating in alternate TBT3 mode)?
It is not. The USB 2.x wires are separate on type-C cables.
> When I connect Thunderbolt 4 dock, the SuperSpeed devices connected to
> dock ports end up on usb2 host controller. However, Low/Full/High-Speed
> devices do end up on usb3 (USB 3.2 xHCI) and not on usb1 (Alder Lake-P
> Thunderbolt 4 USB Controller).
Yes, that's expected the TBT USB controller (on the host) does not
support USB 2.x so it is routed to the PCH one.
> Is there any condition under which the Low/Full/High-Speed devices
> would end up on usb1 (USB 2.0 High-Speed host controller interface
> created for Thunderbolt 4 USB Controller)?
If I understood this right, then no.
> Does the Alder Lake-P Thunderbolt 4 USB Controller even feature USB 2.0
> interface? If not, should the (effectively dummy) usb1 host controller
> even be registered? Is the USB 2.0 functionality provided entirely by
> the Alder Lake PCH USB 3.2 xHCI Host Controller (i.e. when there is no
> TBT3 dock connected)?
It does not.
next prev parent reply other threads:[~2023-05-23 9:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-23 8:53 USB 2.0 host controller for Thunderbolt 4 Tomasz Moń
2023-05-23 9:01 ` Mika Westerberg [this message]
2023-05-23 9:45 ` Moń, Tomasz
2023-05-23 11:03 ` Mathias Nyman
2023-05-23 12:54 ` mika.westerberg
2023-05-23 9:44 ` Oliver Neukum
2023-05-23 9:49 ` Tomasz Moń
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