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This driver allows sending DMA traffic over XDomain connection. Specifically over a loopback connection using either a Thunderbolt/USB4 cable that is connected back to the host router port, or a special loopback dongle that has RX and TX lines crossed. This can be useful at manufacturing floor to check whether Thunderbolt/USB4 ports are functional. The driver exposes debugfs directory under the XDomain service that can be used to configure the driver, start the test and check the results. If a loopback dongle is used the steps to send and receive 1000 packets can be done like: # modprobe thunderbolt_dma_test # echo 1000 > /sys/kernel/debug/thunderbolt/<service_id>/dma_test/packets_to_receive # echo 1000 > /sys/kernel/debug/thunderbolt/<service_id>/dma_test/packets_to_send # echo 1 > /sys/kernel/debug/thunderbolt/<service_id>/dma_test/test # cat /sys/kernel/debug/thunderbolt/<service_id>/dma_test/status When a cable is connected back to host then there are two Thunderbolt services, one is configured for receiving (does not matter which one): # modprobe thunderbolt_dma_test # echo 1000 > /sys/kernel/debug/thunderbolt/<service_a>/dma_test/packets_to_receive # echo 1 > /sys/kernel/debug/thunderbolt/<service_a>/dma_test/test The other one for sending: # echo 1000 > /sys/kernel/debug/thunderbolt/<service_b>/dma_test/packets_to_send # echo 1 > /sys/kernel/debug/thunderbolt/<service_b>/dma_test/test Results can be read from both services status attributes. Signed-off-by: Isaac Hazan <isaac.hazan@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.