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From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org,
	Andreas Noever <andreas.noever@gmail.com>,
	Michael Jamet <michael.jamet@intel.com>,
	Yehezkel Bernat <YehezkelShB@gmail.com>,
	Rajmohan Mani <rajmohan.mani@intel.com>,
	Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>,
	Lukas Wunner <lukas@wunner.de>,
	Alan Stern <stern@rowland.harvard.edu>,
	Mario.Limonciello@dell.com,
	Anthony Wong <anthony.wong@canonical.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 17/22] thunderbolt: Add initial support for USB4
Date: Tue, 1 Oct 2019 16:09:05 +0300
Message-ID: <20191001130905.GO2714@lahna.fi.intel.com> (raw)
In-Reply-To: <20191001124748.GH2954373@kroah.com>

On Tue, Oct 01, 2019 at 02:47:48PM +0200, Greg Kroah-Hartman wrote:
> > -	  Thunderbolt Controller driver. This driver is required if you
> > -	  want to hotplug Thunderbolt devices on Apple hardware or on PCs
> > -	  with Intel Falcon Ridge or newer.
> > +	  USB4 (Thunderbolt) driver. USB4 is the public spec based on
> > +	  Thunderbolt 3 protocol. This driver is required if you want to
> > +	  hotplug Thunderbolt and USB4 compliant devices on Apple
> > +	  hardware or on PCs with Intel Falcon Ridge or newer.
> 
> Wait, did "old" thunderbolt just get re-branded as USB4?

Not but the driver started supporting USB4 as well :)

USB4 is pretty much public spec of Thunderbolt 3 but with some
differences in register layouts (this is because Thunderbolt uses some
vendor specific capabilities which are now moved to more "standard"
places). 

> Because if I have an "old" laptop that needs Thunderbolt support, how am
> I going to know it is now called USB4 instead?

Well the Kconfig option tries to have both names there:

  tristate "USB4 (Thunderbolt) support"

and then

  USB4 (Thunderbolt) driver. USB4 is the public spec based on
  Thunderbolt 3 protocol. This driver is required if you want to hotplug
  Thunderbolt and USB4 compliant devices on Apple hardware or on PCs
  with Intel Falcon Ridge or newer.

and the Kconfig option is still CONFIG_THUNDERBOLT. I know this is
confusing but I don't have better ideas how we can advertise both. I
borrowed this "format" from firewire.

> Shouldn't there just be a new USB4 option that only enables/builds the
> USB4 stuff if selected?  Why would I want all of this additional code on
> my old system if it's not going to do anything at all?

USB4 devices are backward compatible with Thunderbolt 3 so you should be
able to plug in USB4 device to your old Thunderbolt 3 laptop for
example. It goes the other way as well. Some things are optional but for
example USB4 hubs must support also Thunderbolt 3.

Does that clarify?

  reply index

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-01 11:38 [RFC PATCH 00/22] thunderbolt: Add " Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 01/22] thunderbolt: Introduce tb_switch_is_icm() Mika Westerberg
2019-10-01 12:10   ` Greg Kroah-Hartman
2019-10-01 12:46     ` Mika Westerberg
2019-10-01 13:36       ` Mario.Limonciello
2019-10-01 13:48         ` Mika Westerberg
2019-10-01 13:50           ` Mario.Limonciello
2019-10-01 13:52             ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 02/22] thunderbolt: Log switch route string on config read/write timeout Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 03/22] thunderbolt: Log warning if adding switch fails Mika Westerberg
2019-10-01 12:18   ` Greg Kroah-Hartman
2019-10-01 12:48     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 04/22] thunderbolt: Make tb_sw_write() take const parameter Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 05/22] thunderbolt: Add helper macros to iterate over switch ports Mika Westerberg
2019-10-02 14:17   ` Oliver Neukum
2019-10-02 14:28     ` Mika Westerberg
2019-10-06 12:15       ` Lukas Wunner
2019-10-01 11:38 ` [RFC PATCH 06/22] thunderbolt: Add support for lane bonding Mika Westerberg
2019-10-01 12:38   ` Greg Kroah-Hartman
2019-10-01 12:53     ` Mika Westerberg
2019-10-02 14:21       ` Oliver Neukum
2019-10-02 14:30         ` Mika Westerberg
2019-10-03  8:25           ` Oliver Neukum
2019-10-03  8:53             ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 07/22] thunderbolt: Add default linking between ports if not provided by DROM Mika Westerberg
2019-10-01 12:39   ` Greg Kroah-Hartman
2019-10-01 13:14     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 08/22] thunderbolt: Add downstream PCIe port mappings for Alpine and Titan Ridge Mika Westerberg
2019-10-01 12:40   ` Greg Kroah-Hartman
2019-10-01 13:27     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 09/22] thunderbolt: Convert basic adapter register names to follow the USB4 spec Mika Westerberg
2019-10-01 12:41   ` Greg Kroah-Hartman
2019-10-01 13:28     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 10/22] thunderbolt: Convert PCIe adapter register names to use USB4 names Mika Westerberg
2019-10-01 12:42   ` Greg Kroah-Hartman
2019-10-01 11:38 ` [RFC PATCH 11/22] thunderbolt: Convert DP adapter register names to follow the USB4 spec Mika Westerberg
2019-10-01 12:42   ` Greg Kroah-Hartman
2019-10-01 11:38 ` [RFC PATCH 12/22] thunderbolt: Add Display Port CM handshake for Titan Ridge devices Mika Westerberg
2019-10-01 12:44   ` Greg Kroah-Hartman
2019-10-01 13:30     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 13/22] thunderbolt: Add Display Port adapter pairing and resource management Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 14/22] thunderbolt: Add bandwidth management for Display Port tunnels Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 15/22] thunderbolt: Make tb_find_port() available to other files Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 16/22] thunderbolt: Call tb_eeprom_get_drom_offset() from tb_eeprom_read_n() Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 17/22] thunderbolt: Add initial support for USB4 Mika Westerberg
2019-10-01 12:47   ` Greg Kroah-Hartman
2019-10-01 13:09     ` Mika Westerberg [this message]
2019-10-01 14:53       ` Greg Kroah-Hartman
2019-10-01 14:59         ` Mario.Limonciello
2019-10-01 15:13           ` Mika Westerberg
2019-10-01 15:22           ` Greg KH
2019-10-01 15:32             ` Mika Westerberg
2019-10-01 15:07         ` Mika Westerberg
2019-10-01 15:19           ` Greg Kroah-Hartman
2019-10-01 15:26             ` Mika Westerberg
2019-10-01 16:27           ` Oliver Neukum
2019-10-02  8:30             ` Mika Westerberg
2019-10-02  8:39               ` Greg Kroah-Hartman
2019-10-02  8:49                 ` Mika Westerberg
2019-10-01 17:05   ` Mario.Limonciello
2019-10-01 18:14     ` Mario.Limonciello
2019-10-02  8:39       ` Mika Westerberg
2019-10-02 15:09         ` Mario.Limonciello
2019-10-02 15:36           ` Yehezkel Bernat
2019-10-02 16:00             ` Mario.Limonciello
2019-10-03  8:00               ` Mika Westerberg
2019-10-03 14:41                 ` Mario.Limonciello
2019-10-04  7:54                   ` Mika Westerberg
2019-10-04  8:07                     ` Yehezkel Bernat
2019-10-04  8:19                       ` Mika Westerberg
2019-10-04 11:19                         ` Yehezkel Bernat
2019-10-04 14:05                           ` Mario.Limonciello
2019-10-04 14:19                             ` Mario.Limonciello
2019-10-04 14:21                             ` Mika Westerberg
     [not found]                               ` <1570201357.2.0@kellner.me>
2019-10-04 15:16                                 ` Mika Westerberg
2019-10-04 15:22                                   ` Christian Kellner
2019-10-02  8:34     ` Mika Westerberg
2019-10-02 15:04       ` Mario.Limonciello
2019-10-01 11:38 ` [RFC PATCH 18/22] thunderbolt: Make tb_switch_find_cap() available to other files Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 19/22] thunderbolt: Add support for Time Management Unit Mika Westerberg
2019-10-02 16:52   ` Mani, Rajmohan
2019-10-03  8:01     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 20/22] thunderbolt: Add support for USB tunnels Mika Westerberg
2019-10-03  8:42   ` Oliver Neukum
2019-10-03  8:52     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 21/22] thunderbolt: Update documentation with the USB4 information Mika Westerberg
2019-10-01 14:17   ` Mario.Limonciello
2019-10-01 14:21     ` Mika Westerberg
2019-10-01 11:38 ` [RFC PATCH 22/22] thunderbolt: Do not start firmware unless asked by the user Mika Westerberg
2019-10-01 14:43   ` Mario.Limonciello
2019-10-01 14:58     ` Mika Westerberg
2019-10-01 16:53       ` Mario.Limonciello
2019-10-02  8:48         ` Mika Westerberg
2019-10-01 12:49 ` [RFC PATCH 00/22] thunderbolt: Add support for USB4 Greg Kroah-Hartman
2019-10-01 13:42   ` Mika Westerberg

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