Thread (5 messages) read the whole thread 5 messages, 1 author, 2026-06-22
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[RFC PATCH v3 2/4] pps: Drop the !NO_HZ_COMMON dependency from NTP_PPS

From: David Woodhouse <dwmw2@infradead.org>
Date: 2026-06-22 21:18:41
Also in: lkml
Subsystem: pps support, the rest · Maintainers: Rodolfo Giometti, Linus Torvalds

From: David Woodhouse <redacted>

NTP_PPS has been disabled for tickless kernels since it was first
introduced in commit 025b40abe715d ("ntp: add hardpps implementation")
in 2011, with a comment that it "doesn't work on tickless kernels at the
moment".

Whatever the original reasons were, the only *remaining* reason seems to
have been that the accuracy of the time captured by pps_get_ts() was poor
on tickless kernels due to the kernel's per-tick timekeeping mechanism.

A recent change to ktime_get_snapshot_id() which is used by pps_get_ts()
has fixed that problem, by applying a correction to the ::systime field
so that it reports the ideal NTP-corrected time rather than the sanitized
and smoothed version which varies each tick.

Drop the no longer needed dependency.

Signed-off-by: David Woodhouse <redacted>
Assisted-by: Kiro:claude-opus-4.8
---
 drivers/pps/Kconfig | 3 ---
 1 file changed, 3 deletions(-)
diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig
index e1651d51cfc9..3a2c457ed9d8 100644
--- a/drivers/pps/Kconfig
+++ b/drivers/pps/Kconfig
@@ -31,13 +31,10 @@ config PPS_DEBUG
 
 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.
-
 source "drivers/pps/clients/Kconfig"
 
 source "drivers/pps/generators/Kconfig"
-- 
2.54.0
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