[time-nuts] IEEE 1588 PTP support on raspberry pi 4 compute module

[Wojciech Owczarek]

This may be of interest to the original poster...

Apparently 1588 support in the CM4 currently only exists in hardware alone,
and in datasheets. No Linux PTP driver has been written for the BCM
gemac + BCM54210PE PHY combination as of yet:

https://www.raspberrypi.org/forums/viewtopic.php?t=295829
https://github.com/raspberrypi/linux/issues/4151

Datasheets / application notes for the said PHY are not public, so with
this, unfortunately, I would not buy the CM4 unless it had kernel support
for PTP, and I doubt it will come very soon. Not never, but not just yet.

Thanks,
Wojciech

On Tue, 20 Oct 2020 at 22:22, John De Witt <jhdewitt at gmail.com> wrote:

> First post, please be patient with me. Reading the list for a handful of
> years and grateful to the community.
>
> Am interested in low cost GNSS time source to keep clocks during internet
> outage.
>
> Just read that compute module raspberry pi 4 supports IEEE 1588 Precision
> Time Protocol.
>
> Exciting to me ~25usd base for microsecond or better performance over
> network.
>
> Anyone planning on using this? Ethernet is handled by BCM54210 which
> states in data sheet: “IEEE 1588v2 compliant – One-step or two-step clock –
> On-chip timestamping”
>
> Thinking of pairing it with ZED-F9P with PPS would be fun to have PTP GPS
> stratum 1 on LAN for cheap. Ok enough rambling thank you have a nice day.
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Wojciech Owczarek