time: Revert ALWAYS_USE_PERSISTENT_CLOCK compile time optimizaitons

Kay Sievers noted that the ALWAYS_USE_PERSISTENT_CLOCK config,
which enables some minor compile time optimization to avoid
uncessary code in mostly the suspend/resume path could cause
problems for userland.

In particular, the dependency for RTC_HCTOSYS on
!ALWAYS_USE_PERSISTENT_CLOCK, which avoids setting the time
twice and simplifies suspend/resume, has the side effect
of causing the /sys/class/rtc/rtcN/hctosys flag to always be
zero, and this flag is commonly used by udev to setup the
/dev/rtc symlink to /dev/rtcN, which can cause pain for
older applications.

While the udev rules could use some work to be less fragile,
breaking userland should strongly be avoided. Additionally
the compile time optimizations are fairly minor, and the code
being optimized is likely to be reworked in the future, so
lets revert this change.

Reported-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: stable <stable@vger.kernel.org> #3.9
Cc: Feng Tang <feng.tang@intel.com>
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Link: http://lkml.kernel.org/r/1366828376-18124-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 0 insertions, 5 deletions

diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 24510d84efd7..b69692250af4 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -12,11 +12,6 @@ config CLOCKSOURCE_WATCHDOG
 config ARCH_CLOCKSOURCE_DATA
         bool
 
-# Platforms has a persistent clock
-config ALWAYS_USE_PERSISTENT_CLOCK
-        bool
-        default n
-
 # Timekeeping vsyscall support
 config GENERIC_TIME_VSYSCALL
         bool