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[ARM] pxa: fix one-shot timer mode

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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>
This commit is contained in:
Russell King 2007-11-08 23:35:46 +00:00 committed by Russell King
parent c2ec21c5c8
commit 91bc51d8a1
1 changed files with 14 additions and 9 deletions
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23
arch/arm/mach-pxa/time.c
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@ -68,6 +68,7 @@ pxa_ost0_interrupt(int irq, void *dev_id)
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 @@ pxa_ost0_interrupt(int irq, void *dev_id)
* 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 @@ pxa_ost0_interrupt(int irq, void *dev_id)
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 @@ pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
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 @@ pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
/* initializing, released, or preparing for suspend */
raw_local_irq_save(irqflags);
OIER &= ~OIER_E0;
OSSR = OSSR_M0;
raw_local_irq_restore(irqflags);
break;