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For packets with two-step timestamp requests, the hardware timestamp comes back to the driver through a confirmation mechanism of sorts, which allows the driver to confidently bump the successful "pkts" counter. For one-step PTP, the NIC is supposed to autonomously insert its hardware TX timestamp in the packet headers while simultaneously transmitting it. There may be a confirmation that this was done successfully, or there may not. None of the current drivers which implement ethtool_ops :: get_ts_stats() also support HWTSTAMP_TX_ONESTEP_SYNC or HWTSTAMP_TX_ONESTEP_SYNC, so it is a bit unclear which model to follow. But there are NICs, such as DSA, where there is no transmit confirmation at all. Here, it would be wrong / misleading to increment the successful "pkts" counter, because one-step PTP packets can be dropped on TX just like any other packets. So introduce a special counter which signifies "yes, an attempt was made, but we don't know whether it also exited the port or not". I expect that for one-step PTP packets where a confirmation is available, the "pkts" counter would be bumped. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Jakub Kicinski <kuba@kernel.org> Link: https://patch.msgid.link/20250116104628.123555-2-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski <kuba@kernel.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 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.