From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85419C7EE26 for ; Tue, 23 May 2023 09:01:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236292AbjEWJBf (ORCPT ); Tue, 23 May 2023 05:01:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236290AbjEWJBd (ORCPT ); Tue, 23 May 2023 05:01:33 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92798FE for ; Tue, 23 May 2023 02:01:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1684832491; x=1716368491; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=+BYdxmorpWr8KyXWeXZrGuWdoeFoYITDRcDLJHR+ejk=; b=PFY78NnPmZZfwi4YL7kaAeYNpKXqNmkjFnp9YG+Z16WxszaO49KeHaoF 3BSTCzeSsd9H3FYQcCSsazdbl8gMVBU6kzr/QxQ1vThTAFiQUnqDJ7J/J Vt/qoxgk+WLT2kytdOZc6WaetP5psdXyBMIYWXDHrsGu93+4dHYrMYdfB LQJx4Jj07ljZpCnnDTTsP58t8elqB646ie9wIY2fEhfF2mByKOmrAfLQ0 3SZ0XL4Q/8f0nknVSHpl7NzC/SG/xmq/ojj8Td76IgntDefiXteo/W6M2 csL4kkVe1JQbXPGwD62RujRXVqOCrNnDsxPHoTeTnHOkP8thRYmjHh+cH A==; X-IronPort-AV: E=McAfee;i="6600,9927,10718"; a="332796897" X-IronPort-AV: E=Sophos;i="6.00,185,1681196400"; d="scan'208";a="332796897" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 May 2023 02:01:31 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10718"; a="793660623" X-IronPort-AV: E=Sophos;i="6.00,185,1681196400"; d="scan'208";a="793660623" Received: from black.fi.intel.com ([10.237.72.28]) by FMSMGA003.fm.intel.com with ESMTP; 23 May 2023 02:01:29 -0700 Received: by black.fi.intel.com (Postfix, from userid 1001) id 1AF4123E; Tue, 23 May 2023 12:01:32 +0300 (EEST) Date: Tue, 23 May 2023 12:01:32 +0300 From: Mika Westerberg To: Tomasz =?utf-8?Q?Mo=C5=84?= Cc: Andreas Noever , Michael Jamet , Yehezkel Bernat , linux-usb@vger.kernel.org Subject: Re: USB 2.0 host controller for Thunderbolt 4 Message-ID: <20230523090132.GO45886@black.fi.intel.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org 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.