NVIDIA Proposes The Linux Hardware Timestamping Engine
This proposal out of NVIDIA is from their Tegra/embedded side rather than their graphics team. This subsystem would offer real-time timestamping through hardware means with the subsystem having the notion of HTE providers and consumers. "This patch series introduces new subsystem called hardware timestamping engine (HTE). It offers functionality such as timestamping through hardware means in realtime. The HTE subsystem centralizes HTE provider and consumers where providers can register themselves with subsystem and the consumers can request interested entity which could be lines, GPIO, signals or buses," noted NVIDIA's Dipen Patel.
The certain devices have the built in hardware timestamping engine which can monitor sets of system signals, lines, buses etc... in realtime for the state change; upon detecting the change it can automatically store the timestamp at the moment of occurrence. Such functionality may help achieve better accuracy in obtaining timestamp than using software counterparts i.e. ktime and friends.
The proposed documentation goes over more of the details.
In addition to the patches introducing the HTE subsystem and plumbing around GPIOLIB and tools, there is also registering of Tegra194 (Xavier) as a kernel provider as well as having a test driver.
The Hardware Timestamping Engine proposal for Linux can be found on the kernel mailing list for more details. The patches were sent out on Friday night so there hasn't yet been any new discussion on the HTE topic.
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