dTSEC and PTP

[bogdantanasa]

Hi,

I am curious about the accuracy that one can achieve when using PTP to do time synchronization in the context of a T4240 CPU running Linux Yocto. According to the Reference Manual, the CPU is equipped with dTSEC capability (and not eTSEC). Would the accuracy be better or worse if T4240 would have had a eTSEC interface?

Thanks,

[bogdantanasa]

Thanks!

I am curious if QorIQ SDK 1.6 enables the hardware timestamping capabilities of the dTSEC in a T4240. Inspecting the manual (QorIQ-SDK-1.6-IC-RevB.pdf) in Section 8.14.1.6 only the dpaa_1588.c, dpaa_1588.h and dpaa_eth.c files are listed. In contrast, when comparing with QorIQ-SDK-1.9-IC-RevA in Section 7.9.1 one more file is listed dpaa_ptp.c.

Does the PTPd stack in SDK 1.9 allows for better accuracy compared to SDK 1.6 (which seems to miss one)?

[bpe · Accepted solution]

The timestamping unit and IEEE 1588 adjustable timer on eTSEC and

dTSEC are very much similar. Different is only how timestamps are

conveyed to the software, through DPAA or not. This does not

significantly affect the accuracy. Practically achievable numbers

depend on both the network and software implementation. Contact your

distributor or FAE for performance information.

Have a great day,
Platon

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[bogdantanasa]

What technical document one can read about dTSEC, timestamping unit and their interaction with Linux Yocto?

Thanks,

[bpe]

For hardware-level details, refer to T4240DPAARM, Chapter 7, for SDK support details visit the following links:

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Note that T4240 DPAA-controlled multi-rate Ethernet interfaces are not dTSECs, they are next generation peripherals

called mEMAC.