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Implement support for reading the PHC time indirectly via the VIRTCHNL_OP_1588_PTP_GET_TIME operation. Based on some simple tests with ftrace, the latency of the indirect clock access appears to be about ~110 microseconds. This is due to the cost of preparing a message to send over the virtchnl queue. This is expected, due to the increased jitter caused by sending messages over virtchnl. It is not easy to control the precise time that the message is sent by the VF, or the time that the message is responded to by the PF, or the time that the message sent from the PF is received by the VF. For sending the request, note that many PTP related operations will require sending of VIRTCHNL messages. Instead of adding a separate AQ flag and storage for each operation, setup a simple queue mechanism for queuing up virtchnl messages. Each message will be converted to a iavf_ptp_aq_cmd structure which ends with a flexible array member. A single AQ flag is added for processing messages from this queue. In principle this could be extended to handle arbitrary virtchnl messages. For now it is kept to PTP-specific as the need is primarily for handling PTP-related commands. Use this to implement .gettimex64 using the indirect method via the virtchnl command. The response from the PF is processed and stored into the cached_phc_time. A wait queue is used to allow the PTP clock gettime request to sleep until the message is sent from the PF. Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Reviewed-by: Rahul Rameshbabu <rrameshbabu@nvidia.com> Reviewed-by: Simon Horman <horms@kernel.org> Tested-by: Rafal Romanowski <rafal.romanowski@intel.com> Signed-off-by: Mateusz Polchlopek <mateusz.polchlopek@intel.com> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.