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m68knommu: init coldfire timer TRR with n - 1, not n

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The coldfire timer must be initialised to n - 1 if we want it to count n
cycles between each tick interrupt.  This was already fixed, but has been
lost with the conversion to GENERIC_TIMER.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Acked-by: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Philippe De Muyter 2008-06-12 15:21:36 -07:00 committed by Linus Torvalds
parent 67dddaad5d
commit 6c38d85785
1 changed files with 7 additions and 1 deletions
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8
arch/m68knommu/platform/coldfire/timers.c
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@ -111,7 +111,13 @@ void hw_timer_init(void)
__raw_writew(MCFTIMER_TMR_DISABLE, TA(MCFTIMER_TMR));
mcftmr_cycles_per_jiffy = FREQ / HZ;
__raw_writetrr(mcftmr_cycles_per_jiffy, TA(MCFTIMER_TRR));
/*
* The coldfire timer runs from 0 to TRR included, then 0
* again and so on. It counts thus actually TRR + 1 steps
* for 1 tick, not TRR. So if you want n cycles,
* initialize TRR with n - 1.
*/
__raw_writetrr(mcftmr_cycles_per_jiffy - 1, TA(MCFTIMER_TRR));
__raw_writew(MCFTIMER_TMR_ENORI | MCFTIMER_TMR_CLK16 |
MCFTIMER_TMR_RESTART | MCFTIMER_TMR_ENABLE, TA(MCFTIMER_TMR));