configs: enable pps_core module

[lightswitch05]

It seems the pps_core module has disappeared. I've been able to enable the pps_gpio module, but not pps_core. Perhaps this configuration needs to be added? There is also a chance I'm way off base, thank you in advance for having a look at the PR.

[pelwell]

What you've done is changed PPS from being built-in to being an external module, which is a step backwards. ntp_core (enabled with CONFIG_NTP_PPS) is not supported because we set CONFIG_NO_HZ_COMMON=y:

config NTP_PPS
	bool "PPS kernel consumer support"
	depends on !NO_HZ_COMMON
	help
	  This option adds support for direct in-kernel time
	  synchronization using an external PPS signal.

	  It doesn't work on tickless systems at the moment.

But that just means you need an external program to perform the synchronisation - isn't that what chronyd does?

FYI none of this has changed since 5.10, except for PPS being built-in.

[lightswitch05]

Thank you for your response @pelwell. Your example is showing NTP_PPS, but this PR is for CONFIG_PPS. Is that not a different configuration?

The issue I'm having isn't setting up time sync with either chrony or NTP, but just getting the system to recognize the PPS device and create /dev/pps0.

I was torn between the m setting and the y. Or maybe this CONFIG_PPS config is being defaulted to y somewhere else?

[pelwell]

CONFIG_PPS=y is being selected by something else. For each of the defconfigs, run:

$ make ARCH=arm <thing>_defconfig
$ grep PPS .config
$ make ARCH=arm savedefconfig
$ diff <thing>_defconfig defconfig

(or ARCH=arm64)
You'll see that CONFIG_PPS=y is set in all cases, and that when the defconfig is regenerated your setting is dropped.

[lightswitch05]

Ah ok, thank you for clearing that up for me!