Technical Question on TGPIO and TSN/PTP Synchronization in Intel TCC CPUs

[Ali251]

Hello Intel Support Team,

I am currently working with an Intel® TCC-capable CPU (13th Gen Intel® Core™ i9-13900E) and investigating the use of Time-Aware GPIO (TGPIO) in combination with TSN/PTP (IEEE 802.1AS / gPTP) for precise time synchronization.

I would be grateful for clarification on the following points:

1. What is the reference clock source for TGPIO? Is it derived from the Ethernet TSN/PTP clock, an internal oscillator, or another CPU clock domain?
2. How is TGPIO synchronized with the TSN/PTP network clock or PTP grand master? Which hardware, firmware, or driver components are responsible?
3. Are there any documents, example schematics, or pointers to relevant registers within the Intel TCC Tools or drivers that explain this behavior in more detail?

Any guidance or references you can share would be highly appreciated.

Best regards,
SeyedAli SeyedHosseini
TU Dresden

[TheExpertGuy]

1. TGPIO clock source
   TGPIO uses the TCC system clock as its reference. It’s not directly tied to the Ethernet PTP clock, but through Intel’s TCC time services, it can stay aligned with the PTP grandmaster.

2. How it syncs with TSN/PTP
   The synchronization happens through a combination of hardware timestamping in the Ethernet controller and the Intel TCC software stack. Together, they make sure the TGPIO timeline is locked in with the PTP network time.

3. Where to find details

   • The Intel® Time Coordinated Computing Tools User Guide is a great starting point.

   • The TCC Software Stack and API docs (on the Intel Developer Zone) go into how the components work.

   • For register-level details and schematics, you’ll want access to Intel’s Resource and Design Center (RDC). If you don’t have access yet, we can guide you on how to request it.

Intel® Time Coordinated Computing Tools (Intel® TCC Tools) 2022.2.0 Release Notes

[Ali251]

I appreciate your time and assistance.

I would like to also ask:

1)Are there BIOS or firmware settings that allow adjustment of offset, latency, jitter related to TGPIO? 

2) Is there a way (software, driver, diagnostic tools) to measure how well TGPIO tracks the network TSN clock (e.g. Timestamp differences over time, drift, jitter)?

Thanks a lot in advance