From: Alessandro Rubini rubini@unipv.it
Previous code was failing when reading back the timer less than 400us after resetting it. This lead nand operations to incorrectly timeout any now and then. This changes READ_TIMER from negation to subtraction, so after writing 0 to reset it, an immediate read is correctly reported as 0 elapsed ticks.
Signed-off-by: Alessandro Rubini rubini@unipv.it Acked-by: Andrea Gallo andrea.gallo@stericsson.com ---
This is an alternative to V2, which is being posted at the same time. I prefer this approach to that one, as it fixes the problem without switching subsequent code to negative logic.
cpu/arm926ejs/nomadik/timer.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/cpu/arm926ejs/nomadik/timer.c b/cpu/arm926ejs/nomadik/timer.c index 16067c9..991752d 100644 --- a/cpu/arm926ejs/nomadik/timer.c +++ b/cpu/arm926ejs/nomadik/timer.c @@ -34,8 +34,8 @@ #define TICKS_PER_HZ (TIMER_CLOCK / CONFIG_SYS_HZ) #define TICKS_TO_HZ(x) ((x) / TICKS_PER_HZ)
-/* macro to read the 32 bit timer: since it decrements, we invert read value */ -#define READ_TIMER() (~readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0))) +/* macro to read the decrementing 32 bit timer as an increasing count */ +#define READ_TIMER() (0 - readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0)))
/* Configure a free-running, auto-wrap counter with no prescaler */ int timer_init(void)