From: Sven Schnelle <svens@linux.ibm.com>
Date: Thu, 14 Sep 2023 06:58:54 +0000 (+0200)
Subject: s390/time: improve steering precision
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=fc17e992e1fdc5d2e3cf1049073aad0dd3933372;p=linux.git

s390/time: improve steering precision

The common timekeeping code steers the clock by adjusting the multiplier
value of the clock. With the current value of 1000 precision is lost
when the clock is steered with a userspace daemon. Increase the multiplier
and the shift values to increase precision.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 14abad953c025..8357306fb76e7 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -251,8 +251,8 @@ static struct clocksource clocksource_tod = {
 	.rating		= 400,
 	.read		= read_tod_clock,
 	.mask		= CLOCKSOURCE_MASK(64),
-	.mult		= 1000,
-	.shift		= 12,
+	.mult		= 4096000,
+	.shift		= 24,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 	.vdso_clock_mode = VDSO_CLOCKMODE_TOD,
 };