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authorRussell King <rmk@dyn-67.arm.linux.org.uk>2007-11-12 22:48:12 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2008-01-26 15:07:51 +0000
commit4ae7806f8b4bf9a1e74c82f3bd4e91d59bd3d697 (patch)
tree921c819cfa93d70a3e2c5bad328a20c24e3683b3
parenta88264c24c44924a549f3d596b86d611b7ee9909 (diff)
[ARM] pxa: Don't wind OSCR backwards over suspend/resume
OSCR is supposed to monotonically increment; however restoring it to a time prior to OSMR0 may result in it being wound backwards. Instead, if OSMR0 is within the minimum expiry time, wind OSMR0 forwards. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/mach-pxa/time.c21
1 files changed, 12 insertions, 9 deletions
diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c
index 3c4abbf3180..ac0bbad3523 100644
--- a/arch/arm/mach-pxa/time.c
+++ b/arch/arm/mach-pxa/time.c
@@ -181,7 +181,7 @@ static void __init pxa_timer_init(void)
}
#ifdef CONFIG_PM
-static unsigned long osmr[4], oier;
+static unsigned long osmr[4], oier, oscr;
static void pxa_timer_suspend(void)
{
@@ -190,23 +190,26 @@ static void pxa_timer_suspend(void)
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
+ oscr = OSCR;
}
static void pxa_timer_resume(void)
{
+ /*
+ * Ensure that we have at least MIN_OSCR_DELTA between match
+ * register 0 and the OSCR, to guarantee that we will receive
+ * the one-shot timer interrupt. We adjust OSMR0 in preference
+ * to OSCR to guarantee that OSCR is monotonically incrementing.
+ */
+ if (osmr[0] - oscr < MIN_OSCR_DELTA)
+ osmr[0] += MIN_OSCR_DELTA;
+
OSMR0 = osmr[0];
OSMR1 = osmr[1];
OSMR2 = osmr[2];
OSMR3 = osmr[3];
OIER = oier;
-
- /*
- * OSCR0 is the system timer, which has to increase
- * monotonically until it rolls over in hardware. The value
- * (OSMR0 - LATCH) is OSCR0 at the most recent system tick,
- * which is a handy value to restore to OSCR0.
- */
- OSCR = OSMR0 - LATCH;
+ OSCR = oscr;
}
#else
#define pxa_timer_suspend NULL