Update ts2phc gnss_uart_disable Default Setting¶

The default value of the ts2phc instance parameter gnss_uart_disable has changed from true to false.

Overview ¶

When a ts2phc PTP instance is configured with a GNSS source, StarlingX can send vendor-specific UBX commands to the GNSS serial port during startup to disable the module’s unconnected UART interfaces. This behavior is controlled by the gnss_uart_disable parameter.

Previously, this parameter defaulted to true, so the UART-disable commands were sent for every ts2phc instance. These commands are not applicable to all GNSS modules. On hardware with properly connected UART interfaces, sending them is unnecessary and can interfere with normal operation.

The default is now false. By default, no UART-disable commands are sent. Deployments that require this behavior can re-enable it per instance, as described below.

Note

This is a behavioral change. If you previously relied on the default true behavior without explicitly setting the parameter, the UART-disable commands will no longer be sent after upgrade. If GNSS noise or related faults reappear, re-enable the behavior using the procedure below.

Re-enable the Disable UART Behavior ¶

The following procedure describes how to re-enable the old behavior, and disable the module’s unconnected UART.

Re-enable gnss_uart_disable when a GNSS fault is observed that is caused by noise on the module’s unconnected UART interfaces. Typical symptoms include:

GNSS signal-loss alarms that clear when the module’s unconnected UART interfaces are disabled.
Intermittent loss of GNSS lock on affected E810-based NICs with unconnected UART interfaces.
Unexpected NMEA or GNSS errors reported by ts2phc in the logs.

Set the gnss_uart_disable parameter to true on the affected ts2phc instance and apply the configuration.

Procedure

Add the parameter to the ts2phc instance.
```
~(keystone_admin)$ system ptp-instance-parameter-add <ts2phc-instance-name> gnss_uart_disable=true
```
Replace <ts2phc-instance-name> with the name of your ts2phc instance.
Apply the PTP configuration to each host that uses the instance.
```
~(keystone_admin)$ system ptp-instance-apply
```
Verify that the parameter is set on the instance.
```
~(keystone_admin)$ system ptp-instance-show <ts2phc-instance-name>
```
The parameters field should include gnss_uart_disable=true.

Note

The UART-disable commands are only sent during startup, not during a runtime apply. A host lock/unlock, or a service restart, may be required for the change to take effect on a running host.

Restore Default Behavior ¶

To restore the new default behavior (no UART-disable commands), either set the parameter to false or remove it.

~(keystone_admin)$ system ptp-instance-parameter-add <ts2phc-instance-name> gnss_uart_disable=false
~(keystone_admin)$ system ptp-instance-apply

Alternatively, remove the parameter entirely:

~(keystone_admin)$ system ptp-instance-parameter-delete <ts2phc-instance-name> gnss_uart_disable=true
~(keystone_admin)$ system ptp-instance-apply