From: Alessandro Rubini rubini@unipv.it
Previously the code wrote 0 to reset the counter and used negation to read an increasing value from the register. However, a readback before 400us still returned 0, which was reported as 1780 seconds, thus nand failed to work any now and then. As suggested by Wolfgang Denk, this changes READ_TIMER to just return the hardware counter (a declerasing one) and changes code using the value. Compile-tested only, at this point.
Signed-off-by: Alessandro Rubini rubini@unipv.it Acked-by: Andrea Gallo andrea.gallo@stericsson.com ---
Please note that V3 is being posted at the same time. I prefer V3 to this V2, but V2 is how I've been asked to do things.
cpu/arm926ejs/nomadik/timer.c | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/cpu/arm926ejs/nomadik/timer.c b/cpu/arm926ejs/nomadik/timer.c index 16067c9..c7dd65d 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 32 bit timer: note however that the count decreases */ +#define READ_TIMER() readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0))
/* Configure a free-running, auto-wrap counter with no prescaler */ int timer_init(void) @@ -46,7 +46,7 @@ int timer_init(void) return 0; }
-/* Restart counting from 0 */ +/* Restart counting from 0 (still, it is a decrementing counter) */ void reset_timer(void) { writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); /* Immediate effect */ @@ -55,7 +55,7 @@ void reset_timer(void) /* Return how many HZ passed since "base" */ ulong get_timer(ulong base) { - return TICKS_TO_HZ(READ_TIMER()) - base; + return TICKS_TO_HZ(-READ_TIMER()) - base; }
/* Delay x useconds */ @@ -63,8 +63,8 @@ void udelay(unsigned long usec) { ulong ini, end;
- ini = READ_TIMER(); - end = ini + USEC_TO_COUNT(usec); - while ((signed)(end - READ_TIMER()) > 0) + ini = READ_TIMER(); /* decrementing value */ + end = ini - USEC_TO_COUNT(usec); + while ((signed)(READ_TIMER() - end) > 0) ; }