rtc-bfin: fix state restoration when resuming
authorMike Frysinger <vapier@gentoo.org>
Thu, 9 Sep 2010 23:37:29 +0000 (16:37 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 10 Sep 2010 01:57:22 +0000 (18:57 -0700)
commitb6de860651d5a9e56ba4f4e3edc1aa52ac2ac849
tree59b41da9289132e7e494ebb49adef7bafdbac9cf
parent110b7e9698601b28f313c2c560d51a8b1c742002
rtc-bfin: fix state restoration when resuming

Much (but not all) of the RTC state is kept in the RTC peripheral which
has its own power domain.  Periodically (1 HZ), that state is synced from
one power domain to the other (peripheral->core).  When we are resuming,
we need to wait for the sync to occur so that we don't get a mismatch of
reading undefined state in the rest of the driver.

Further, once the externally maintained bits have been synced back into
the core, we then need to restore the bits maintained in the core.  In our
particular case, that is just the write completion interrupt bit.

If we don't do any of this, working with the RTC causes ~5 second delays
from time to time after waking up due to the write completion interrupt
never firing.

Reported-by: Michael Dean <mdean@aeronix.com>
Reported-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/rtc/rtc-bfin.c