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983e0e4e87
Add SOF_TIMESTAMPING_TX_COMPLETION, for requesting a software timestamp when hardware reports a packet completed. Completion tstamp is useful for Bluetooth, as hardware timestamps do not exist in the HCI specification except for ISO packets, and the hardware has a queue where packets may wait. In this case the software SND timestamp only reflects the kernel-side part of the total latency (usually small) and queue length (usually 0 unless HW buffers congested), whereas the completion report time is more informative of the true latency. It may also be useful in other cases where HW TX timestamps cannot be obtained and user wants to estimate an upper bound to when the TX probably happened. Signed-off-by: Pauli Virtanen <pav@iki.fi> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
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 reStructuredText 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.