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Commit 779d2089 authored by David Brownell's avatar David Brownell Committed by Linus Torvalds
Browse files

rtc_hctosys expects RTCs in UTC (doc) 



The RTC "hctosys" mechanism expects that RTC clock will use UTC, not local
time (e.g.  PST).  Say so in Kconfig and in the kernel message.

(Strictly speaking, the RTC clock should be tracking the POSIX epoch.  That's
not worth going into here.  Goofing timezones means clocks are wrong by many
hours; the POSIX-v-UTC differences just cost seconds.)

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Acked-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1299342b

drivers/rtc/Kconfig

+3 −1
Original line number Diff line number Diff line
@@ -36,7 +36,9 @@ config RTC_HCTOSYS_DEVICE 
	help

	  The RTC device that will be used to (re)initialize the system

	  clock, usually rtc0.  Initialization is done when the system

	  starts up, and when it resumes from a low power state.

	  starts up, and when it resumes from a low power state.  This

	  device should record time in UTC, since the kernel won't do

	  timezone correction.



	  The driver for this RTC device must be loaded before late_initcall

	  functions run, so it must usually be statically linked.

drivers/rtc/hctosys.c

+2 −2
Original line number Diff line number Diff line
@@ -47,8 +47,8 @@ static int __init rtc_hctosys(void) 
			do_settimeofday(&tv);



			dev_info(rtc->dev.parent,

				"setting the system clock to "

				"%d-%02d-%02d %02d:%02d:%02d (%u)\n",

				"setting system clock to "

				"%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n",

				tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,

				tm.tm_hour, tm.tm_min, tm.tm_sec,

				(unsigned int) tv.tv_sec);