Linux PTP versions on the Ouster Sensor

Software
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The Ouster sensors achieve PTP time synchronization through the use of verbatim Linux PTP (aka ptp4l).

LinuxPTP versions

Here are the linuxptp versions listed by Ouster firmware version:

  • Ouster FW v3.0.1:
    • linuxptp cortexa53 3.1.1
  • Ouster FW v3.1.0:
    • linuxptp cortexa53 4.1

Patch for protocol version

Additionally, there is a recommended patch for customers to force their client PTP_VERSION (protocol version not linuxptp version) to 2.0 instead of 2.1.

Ouster sensors advertise v2.0 linuxptp protocol to avoid customer compatibility problems with post v4.0 linuxptp versions

Here is a link to the source/fix of the problem in the PTP mailing list.

Date: Mon, 2 Oct 2023 11:28:37 -0700
Subject: [PATCH] msg: rollback PTP_VERSION to 2.0 to workaround hw issues

  • Many devices have issues with timestamping inbound/outbound packets
    with the version set v2.1 which results in breakage.
  • Rolling this back seems to have almost no impact other than we
    advertise a lower version.
  • Introduced by commit: 2a2532d66121d0060b042c5bd6020a62153f1e0a
---
msg.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/msg.h b/msg.h
index 484435d..ffc49d4 100644
--- a/msg.h
+++ b/msg.h
@@ -32,7 +32,7 @@
 
 # Version definition for IEEE 1588-2019 
 #define PTP_MAJOR_VERSION	2
-#define PTP_MINOR_VERSION	1
+#define PTP_MINOR_VERSION	0 /* BUG: rollback for customer hw compatibility */
#define PTP_VERSION		(PTP_MINOR_VERSION << 4 | PTP_MAJOR_VERSION)
#define MAJOR_VERSION_MASK	0x0f`

--
2.34.1