ptp_sendmsg() called a blocking recvmsg(state->tx_socket, ...) right
after sending a Delay_Req whenever hardware_ts was set, assuming a
Linux-style MSG_ERRQUEUE/loopback semantics NuttX does not have.
Since tx_socket and event_socket share the same underlying
connection, this call instead blocked on and consumed whatever PTP
packet arrived next on the wire — almost always the Delay_Resp,
which typically arrives within milliseconds of the request. Its
payload was read into a local buffer that went out of scope on
return, so the packet never reached ptp_process_rx_packet() and
path_delay_ns stayed at 0 in -H mode. t3 is now captured locally
via ptp_gettime(), the same way -S mode already did, until
hardware TX timestamping is supported.
Also replaces the path delay heuristic in ptp_process_delay_resp()
(which derived an approximation of (t2-t1) from path_delay_ns and
last_delta_ns, only valid once the clock had already converged) with
the canonical IEEE 1588-2008 §11.3 formula: store (t2-t1) directly
from Sync/Follow_Up as sync_diff_ns, then average it with (t4-t3)
from the Delay_Req/Delay_Resp exchange. Relaxes the path delay
ceiling to 10ms unconditionally, since Delay_Req's t3 is software-
timestamped in both modes until hardware TX timestamping is supported.
Assisted-by: Claude:claude-sonnet-5
Assisted-by: Gemini:gemini-3.8-flash-medium
Signed-off-by: Daniel P. Carvalho <danieloak@gmail.com>
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