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sys_linux: don't require configurable pin for external PPS

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Some PHCs that have a PPS input don't have configurable pins (their
function is hardcoded). Accept a negative pin index to skip the pin
configuration before requesting external timestamping.
This commit is contained in:
Miroslav Lichvar 2022-02-23 11:31:24 +01:00
parent 663dde1ad7
commit 3196630fb9
2 changed files with 5 additions and 3 deletions
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6
doc/chrony.conf.adoc
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@ -511,8 +511,10 @@ Note that some PTP clocks cannot be configured to timestamp only assert or
clear events, and it is necessary to use the *width* option to filter wrong
PPS samples.
*pin*=_index_::::
This option specifies the index of the pin to which is connected the PPS
signal. The default value is 0.
This option specifies the index of the pin which should be enabled for the
PPS timestamping. If the PHC does not have configurable pins (i.e. the channel
function is fixed), the index needs to be set to -1 to disable the pin
configuration. The default value is 0.
*channel*=_index_::::
This option specifies the index of the channel for the PPS mode. The default
value is 0.

2
sys_linux.c
View file

@ -1008,7 +1008,7 @@ SYS_Linux_SetPHCExtTimestamping(int fd, int pin, int channel,
pin_desc.func = enable ? PTP_PF_EXTTS : PTP_PF_NONE;
pin_desc.chan = channel;
if (ioctl(fd, PTP_PIN_SETFUNC, &pin_desc)) {
if (pin >= 0 && ioctl(fd, PTP_PIN_SETFUNC, &pin_desc)) {
DEBUG_LOG("ioctl(%s) failed : %s", "PTP_PIN_SETFUNC", strerror(errno));
return 0;
}