[ARM] pxa: fix one-shot timer mode
One-shot timer mode on PXA has various bugs which prevent kernels
build with NO_HZ enabled booting. They end up spinning on a
permanently asserted timer interrupt because we don't properly
clear it down - clearing the OIER bit does not stop the pending
interrupt status. Fix this in the set_mode handler as well.
Moreover, the code which sets the next expiry point may race with
the hardware, and we might not set the match register sufficiently
in the future. If we encounter that situation, return -ETIME so
the generic time code retries.
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c
index a2d45d7..fbfa192 100644
--- a/arch/arm/mach-pxa/time.c
+++ b/arch/arm/mach-pxa/time.c
@@ -68,6 +68,7 @@
if (c->mode == CLOCK_EVT_MODE_ONESHOT) {
/* Disarm the compare/match, signal the event. */
OIER &= ~OIER_E0;
+ OSSR = OSSR_M0;
c->event_handler(c);
} else if (c->mode == CLOCK_EVT_MODE_PERIODIC) {
/* Call the event handler as many times as necessary
@@ -100,9 +101,9 @@
* anything that might put us "very close".
*/
#define MIN_OSCR_DELTA 16
- do {
+ do {
OSSR = OSSR_M0;
- next_match = (OSMR0 += LATCH);
+ next_match = (OSMR0 += LATCH);
c->event_handler(c);
} while (((signed long)(next_match - OSCR) <= MIN_OSCR_DELTA)
&& (c->mode == CLOCK_EVT_MODE_PERIODIC));
@@ -114,14 +115,16 @@
static int
pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev)
{
- unsigned long irqflags;
+ unsigned long flags, next, oscr;
- raw_local_irq_save(irqflags);
- OSMR0 = OSCR + delta;
- OSSR = OSSR_M0;
+ raw_local_irq_save(flags);
OIER |= OIER_E0;
- raw_local_irq_restore(irqflags);
- return 0;
+ next = OSCR + delta;
+ OSMR0 = next;
+ oscr = OSCR;
+ raw_local_irq_restore(flags);
+
+ return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
}
static void
@@ -132,15 +135,16 @@
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
raw_local_irq_save(irqflags);
- OSMR0 = OSCR + LATCH;
OSSR = OSSR_M0;
OIER |= OIER_E0;
+ OSMR0 = OSCR + LATCH;
raw_local_irq_restore(irqflags);
break;
case CLOCK_EVT_MODE_ONESHOT:
raw_local_irq_save(irqflags);
OIER &= ~OIER_E0;
+ OSSR = OSSR_M0;
raw_local_irq_restore(irqflags);
break;
@@ -149,6 +153,7 @@
/* initializing, released, or preparing for suspend */
raw_local_irq_save(irqflags);
OIER &= ~OIER_E0;
+ OSSR = OSSR_M0;
raw_local_irq_restore(irqflags);
break;