kernel/Documentation/admin-guide/thunderbolt.rst, branch linux-rolling-stable

thunderbolt: Update NVM firmware upgrade documentation

2025-11-03T11:01:46Z

Update guide about firmware upgrade of Thunderbolt devices, replacing outdated recommendations with the use of modern "fwupd" tool. Signed-off-by: Alan Borzeszkowski Signed-off-by: Mika Westerberg

Documentation: ABI: Update WMI device paths in ABI docs

2025-06-13T09:33:31Z

The WMI driver core might append an ID to the WMI device name to avoid name collisions in case multiple WMI devices with the same GUID are present. Update all sysfs path referring to WMI devices to inform users about this important detail. Signed-off-by: Armin Wolf Link: https://lore.kernel.org/r/20250610055526.23688-1-W_Armin@gmx.de Reviewed-by: Ilpo Järvinen Signed-off-by: Ilpo Järvinen

Documentation/admin-guide: Document Thunderbolt/USB4 tunneling events

2025-04-24T05:24:39Z

Add documentation about the Thunderbolt/USB4 tunneling events to the user’s and administrator’s guide. Signed-off-by: Alan Borzeszkowski Signed-off-by: Mika Westerberg

docs: thunderbolt: Allow creating cross-references for ABI

2025-02-18T20:42:46Z

Now that Documentation/ABI is processed by automarkup, let it generate cross-references for the corresponding ABI file. Signed-off-by: Mauro Carvalho Chehab Acked-by: Mika Westerberg Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/a655e770e1446f91088f579b79ae890a19771119.1739254867.git.mchehab+huawei@kernel.org

thunderbolt: Add support for retimer NVM upgrade when there is no link

2021-06-01T07:53:31Z

With help from platform firmware (ACPI) it is possible to power on retimers even when there is no USB4 link (e.g nothing is connected to the USB4 ports). This allows us to bring the USB4 sideband up so that we can access retimers and upgrade their NVM firmware. If the platform has support for this, we expose two additional attributes under USB4 ports: offline and rescan. These can be used to bring the port offline, rescan for the retimers and put the port online again. The retimer NVM upgrade itself works the same way than with cable connected. Signed-off-by: Rajmohan Mani Co-developed-by: Mika Westerberg Signed-off-by: Mika Westerberg Reviewed-by: Greg Kroah-Hartman

thunderbolt: Add support for PCIe tunneling disabled (SL5)

2021-02-04T07:45:24Z

Recent Intel Thunderbolt firmware connection manager has support for another security level, SL5, that disables PCIe tunneling. This option can be turned on from the BIOS. When this is set the driver exposes a new security level "nopcie" to the userspace and hides the authorized attribute under connected devices. While there we also hide it when "dponly" security level is enabled since it is not really usable in that case anyway. Signed-off-by: Mika Westerberg Acked-by: Yehezkel Bernat

thunderbolt: Add support for de-authorizing devices

2021-01-15T07:53:06Z

In some cases it is useful to be able de-authorize devices. For example if user logs out the userspace can have a policy that disconnects PCIe devices until logged in again. This is only possible for software based connection manager as it directly controls the tunnels. For this reason make the authorized attribute accept writing 0 which makes the software connection manager to tear down the corresponding PCIe tunnel. Userspace can check if this is supported by reading a new domain attribute deauthorization, that holds 1 in that case. While there correct tb_domain_approve_switch() kernel-doc and description of authorized attribute to mention that it is only about PCIe tunnels. Cc: Christian Kellner Signed-off-by: Mika Westerberg Acked-by: Yehezkel Bernat

thunderbolt: Add support for on-board retimers

2020-06-22T16:58:32Z

USB4 spec specifies standard access to retimers (both on-board and cable) through USB4 port sideband access. This makes it possible to upgrade their firmware in the same way than we already do with the routers. This enumerates on-board retimers under each USB4 port when the link comes up and adds them to the bus under the router the retimer belongs to. Retimers are exposed in sysfs with name like :. where device is the router the retimer belongs to, port is the USB4 port the retimer is connected to and index is the retimer index under that port (starting from 1). This applies to the upstream USB4 port as well so if there is on-board retimer between the port and the router it is also added accordingly. At this time we do not add cable retimers but there is no techincal restriction to do so in the future if needed. It is not clear whether it makes sense to upgrade their firmwares and at least Thunderbolt 3 cables it has not been done outside of lab environments. The sysfs interface is made to follow the router NVM upgrade to make it easy to extend the existing userspace (fwupd) to handle these as well. Signed-off-by: Kranthi Kuntala Co-developed-by: Mika Westerberg Signed-off-by: Mika Westerberg

thunderbolt: Update documentation with the USB4 information

2019-12-18T14:41:41Z

Update user's and administrator's guide to mention USB4, how it relates to Thunderbolt and and how it is supported in Linux. While there add the missing SPDX identifier to the document. Signed-off-by: Mika Westerberg Link: https://lore.kernel.org/r/20191217123345.31850-10-mika.westerberg@linux.intel.com Signed-off-by: Greg Kroah-Hartman

thunderbolt: Export IOMMU based DMA protection support to userspace

2018-12-05T09:01:56Z

Recent systems with Thunderbolt ports may support IOMMU natively. In practice this means that Thunderbolt connected devices are placed behind an IOMMU during the whole time it is connected (including during boot) making Thunderbolt security levels redundant. This is called Kernel DMA protection [1] by Microsoft. Some of these systems still have Thunderbolt security level set to "user" in order to support OS downgrade (the older version of the OS might not support IOMMU based DMA protection so connecting a device still relies on user approval). Export this information to userspace by introducing a new sysfs attribute (iommu_dma_protection). Based on it userspace tools can make more accurate decision whether or not authorize the connected device. In addition update Thunderbolt documentation regarding IOMMU based DMA protection. [1] https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt Signed-off-by: Mika Westerberg Reviewed-by: Yehezkel Bernat