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| author | Mark Brown <broonie@kernel.org> | 2026-05-29 23:00:29 +0100 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2026-05-29 23:00:29 +0100 |
| commit | 9bc5df932dde692c37a2ad7d1801c9b65d0ddbb5 (patch) | |
| tree | 62b96f13021d05d5a8a00d2fdee62be091a84db8 /Documentation | |
| parent | 9394de50f7ac760fe5ae2eea0fa184185f2cdc3a (diff) | |
| parent | 2c5d2d3c3f70cde2565d7b279b544893a2035842 (diff) | |
| download | linux-next-history-9bc5df932dde692c37a2ad7d1801c9b65d0ddbb5.tar.gz | |
Merge branch 'next' of https://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt.git
# Conflicts:
# drivers/thunderbolt/property.c
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/configfs-thunderbolt_stream | 83 | ||||
| -rw-r--r-- | Documentation/admin-guide/thunderbolt.rst | 61 |
2 files changed, 144 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/configfs-thunderbolt_stream b/Documentation/ABI/testing/configfs-thunderbolt_stream new file mode 100644 index 0000000000000..7abc6b73a1e4c --- /dev/null +++ b/Documentation/ABI/testing/configfs-thunderbolt_stream @@ -0,0 +1,83 @@ +What: /sys/kernel/config/thunderbolt/stream/<xdomain>.<service> +Date: Sep 2026 +KernelVersion: v7.2 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: + Configuration group for a stream Thunderbolt/USB4 + service. It is possible to create groups even if there + is no connection yet to the other host. Once a + connection established and there is stream service on + the remote side that matches, this configuration is + applied to it. + + To find the service name you can run tblist from tbtools [1]: + + # tblist -A + ... + Domain 0 Route 3 Index 0: stream + + [1] https://github.com/intel/tbtools + +What: /sys/kernel/config/thunderbolt/stream/<xdomain>.<service>/$name +Date: Sep 2026 +KernelVersion: v7.2 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: + Creates new stream with $name and fills it with the + default values. If there is an advertised remote stream + with the same name, uses its values as the default. + +What: /sys/kernel/config/thunderbolt/stream/<xdomain>.<service>/$name/index +Date: Sep 2026 +KernelVersion: v7.2 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: + This matches the X in /dev/tbstreamX and allows userspace + to map the configfs directory to the corresponding character + device. + +What: /sys/kernel/config/thunderbolt/stream/<xdomain>.<service>/$name/in_hopid +Date: Sep 2026 +KernelVersion: v7.2 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: + In HopID used with the read path of the tunnel. Available HopIDs + for tunneling start from 8. You can pass also -1 for automatic + allocation. The allocated value can be read here. Writing 0 will + de-allocate if the stream is not in use. + + To figure out the maximum HopID you can run tbget from + tbtools for the lane adapter. For example below we check + for lane adapter number 1 (first USB4 port): + + # tbget -r 0 -a 1 -D ADP_CS_5.Max\ Input\ HopID + 19 + + This allows to use anything between 8 and 19 inclusive. + +What: /sys/kernel/config/thunderbolt/stream/<xdomain>.<service>/$name/out_hopid +Date: Sep 2026 +KernelVersion: v7.2 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: + Out HopID used with the write path of the tunnel. Available HopIDs + for tunneling start from 8. You can pass also -1 for automatic + allocation. The allocated value can be read here. Writing 0 will + de-allocate if the stream is not in use. See @in_hopid + for how to figure out the maximum HopID. + +What: /sys/kernel/config/thunderbolt/stream/<xdomain>.<service>/$name/ring_size +Date: Sep 2026 +KernelVersion: v7.2 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: + Size of the TX/RX rings. Can be adjusted between 32 and + 4096. The default is 256. + +What: /sys/kernel/config/thunderbolt/stream/<xdomain>.<service>/$name/throttling +Date: Sep 2026 +KernelVersion: v7.2 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: + Interrupt throttling rate in ns. Lower values can give + better latency. The default is 8192 ns. diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst index 89df26553aa03..91a6cb1099889 100644 --- a/Documentation/admin-guide/thunderbolt.rst +++ b/Documentation/admin-guide/thunderbolt.rst @@ -373,6 +373,67 @@ port which are named like ``thunderbolt0`` and so on. From this point you can either use standard userspace tools like ``ip`` to configure the interface or let your GUI handle it automatically. +Streaming data directly over Thunderbolt cable +---------------------------------------------- +In addition to Thunderbolt networking (aka. USB4NET) Linux supports +streaming data directly over a cable as well (aka. USB4STREAM). This is +possible through ``thunderbolt-stream`` driver. + +Similarly to ``thunderbolt-net`` you load the driver first on one end:: + + host1 # modprobe thunderbolt-stream + +Then you configure it via ``ConfigFS``:: + + host1 # cd /sys/kernel/config/thunderbolt/stream + host1 # mkdir -p 0-1.0/data + host1 # cd 0-1.0 + host1 # echo -1 > data/in_hopid + host1 # echo -1 > data/out_hopid + +This information is automatically announced to the other side via +XDomain properties so if you have cable connected the other side knows +that there is a stream named ``data`` available and can configure it for +you automatically:: + + host2 # cd /sys/kernel/config/thunderbolt/stream + host2 # mkdir -p 0-3.0/data + +Here we used auto-configuration but you can configure it manually too. +In that case you need to fill ``in_hopid`` and ``out_hopid`` accordingly. +If you set them to ``-1`` the next available HopID is used which is +typically what we want. + +Once they are configured you can use ``/dev/tbstreamX`` on both sides to +transfer data:: + + host2 # cat /dev/tbstream0 + host1 # dmesg > /dev/tbstream0 + +Once you are done with the stream you can remove them:: + + host2 # cd /sys/kernel/config/thunderbolt/stream + host2 # rmdir -p 0-1.0/data + host1 # cd /sys/kernel/config/thunderbolt/stream + host1 # rmdir -p 0-3.0/data + +Since streams are essentially files you can use any existing application +that supports ``read(2)`` and ``write(2)`` in some form. + +It is possible to have more than one stream and you can have both stream +and ``thunderbolt-net`` in use simultaneously. For example we can create +two streams with name ``control`` and ``data`` like this:: + + host1 # cd /sys/kernel/config/thunderbolt/stream + host1 # mkdir 0-1.0 + host1 # cd 0-1.0 + host1 # mkdir control + host1 # mkdir data + +Then you have ``/dev/tbstream0`` for ``control`` and ``/dev/tbstream1`` +for ``data``. Before you can use them you need to configure them as +shown above for the one stream case. + Forcing power ------------- Many OEMs include a method that can be used to force the power of a |