On 3/31/2021 8:56 AM, Dhanuka, Anmol via Linuxptp-users wrote:
> 1. The configuration for one-step sync timestamp insertion in DP83640
> (Page 5, register 0x0016, bit 15) is getting cleared on running
> ptp4l. Is there some option I need to provide in the ptp4l command
> to run one-step mode?
You need to enable some configuration options to use one-step mode in
ptp4l. Check the manual page and search for one step.
> 2. Can you please clarify how is ptp4l fetching the hardware timestamps
> from the PHY? Is it polling for some event hardware interrupts to
> read the timestamp registers of PHY? Want to understand if I missed
> routing some signals in Vivado.
ptp4l relies on the standard Linux socket interface for timestamps where
a timestamp is reported for a packet over the socket error queue. ptp4l
will send a packet with the timestamp request, and then wait for about
1ms on the socket error queue to get a response back.
It's up to the driver and hardware how the internal PHY timestamp is
captured, and not something ptp4l itself cares about. This is a device
driver question you might want to ask the driver developer. If that's
you, then I suggest reading the documentation files for PTP from the
Linux kernel documentation for how to implement the driver correctly.
> 3. If I want to enable software based timestamping options as well,
> which kernel options need to be enabled?
>
Your driver must be implemented to call the proper software timestamp
function in its transmit path, and it must correctly enable the
SOF_TIMESTAMPING_SOFTWARE flag in its ethtool .get_ts_info callback.
>From the output you gave, it appears that the driver does not support
software timestamps.
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