From 6c38d8578545482fe45d6e6ea37be02a2e1bb289 Mon Sep 17 00:00:00 2001 From: Philippe De Muyter Date: Thu, 12 Jun 2008 15:21:36 -0700 Subject: [PATCH] m68knommu: init coldfire timer TRR with n - 1, not n 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 Acked-by: Greg Ungerer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/m68knommu/platform/coldfire/timers.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/m68knommu/platform/coldfire/timers.c b/arch/m68knommu/platform/coldfire/timers.c index ba5a9f32ebd4..454f25493491 100644 --- a/arch/m68knommu/platform/coldfire/timers.c +++ b/arch/m68knommu/platform/coldfire/timers.c @@ -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));