The kernel documentation states the ability to use POSIX timers with the PTP
hardware clocks. This does not appear to be implemented in the ptp
subsystem drivers. What is preventing this timer interface from being
implemented?
Previous discussions[1] indicate the PHC timer functionality was less
effective than using nanosleep with the system clock for driving a gpio.
However, the timers are still useful if they trigger a hardware event. For
example, user software configures a timer on a PHC, the timer fires both an
event in hardware to be used by external hardware and a notification back to
the user. That event to external hardware would occur precisely from the
phc time. The user would be notified of the event via the timer interface.
The latency from software responding to the timer and then firing an event
on a gpio would be eliminated.
I have an FPGA implementation of a PTP device and would like to add support
for the ptp timers. This would allow my FPGA implementation to interface
with external sensors and hardware using the ptp timer. What would be
required to get the POSIX timer interface flushed out in the ptp subsystem?
[1] https://sourceforge.net/p/linuxptp/mailman/message/35535965/
Thanks,
Alex Fontaine
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