[U-Boot] [PATCH (repost)] Nomadik: fix reset_timer()
From: Alessandro Rubini rubini@unipv.it
The timer decrements and READ_TIMER() negates the value read. Writing 0 in reset_timer() is this wrong, as a readback before 400us will read back 0 and will report 1780 seconds, so nand operations did timeout. This patch writes ~0 in reset_timer to prevent this.
Signed-off-by: Alessandro Rubini rubini@unipv.it Acked-by: Andrea Gallo andrea.gallo@stericsson.com ---
This must be applied for nand to work. It's a simple bugfix so I think it got simply forgotten.
BTW: I got no feedback for the lcd/keypad stuff, neither positive nor negative. Shall I repost my current status in that regard?
thanks /alessandro
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..2115b71 100644 --- a/cpu/arm926ejs/nomadik/timer.c +++ b/cpu/arm926ejs/nomadik/timer.c @@ -46,10 +46,10 @@ int timer_init(void) return 0; }
-/* Restart counting from 0 */ +/* Restart counting from ~0 (can't be 0, since READ_TIMER negates) */ void reset_timer(void) { - writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); /* Immediate effect */ + writel(~0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); /* Immediate effect */ }
/* Return how many HZ passed since "base" */
Dear Alessandro Rubini,
In message 20091103121250.GA8577@mail.gnudd.com you wrote:
From: Alessandro Rubini rubini@unipv.it
The timer decrements and READ_TIMER() negates the value read. Writing 0 in reset_timer() is this wrong, as a readback before 400us will read back 0 and will report 1780 seconds, so nand operations did timeout. This patch writes ~0 in reset_timer to prevent this.
Signed-off-by: Alessandro Rubini rubini@unipv.it Acked-by: Andrea Gallo andrea.gallo@stericsson.com
This must be applied for nand to work. It's a simple bugfix so I think it got simply forgotten.
Um... why is READ_TIMER doing such a stupid thing as negating values? This is not what it is supposed to do - as the name says, it should _read_ the _timer_. There is no mentioning of "NEgATE" anywhere?
Best regards,
Wolfgang Denk
Um... why is READ_TIMER doing such a stupid thing as negating values?
Because the counter counts down. I could have returns "0 - value" or "~value". Since I chose the latter initially, this fix keeps the same approach. I can't return the value I read, since it goes backwards.
/alessandro
Dear Alessandro Rubini,
In message 20091103152354.GA12451@mail.gnudd.com you wrote:
Um... why is READ_TIMER doing such a stupid thing as negating values?
Because the counter counts down. I could have returns "0 - value" or "~value". Since I chose the latter initially, this fix keeps the same approach. I can't return the value I read, since it goes backwards.
Well, to me READ_TIMER() sounds like a function/macro to read some value from some timer; if that timer counts doen, then successive calls to that macro/function would return decreasing values. Counting up or down is a property of the specific timer and should be handled elsewhere; such policy does IMHO not belong into some accessor function.
Best regards,
Wolfgang Denk
Well, to me READ_TIMER() sounds like a function/macro to read some value from some timer; if that timer counts doen, then successive calls to that macro/function would return decreasing values. Counting up or down is a property of the specific timer and should be handled elsewhere; such policy does IMHO not belong into some accessor function.
Well, I thought this was an easy fix. Unfortunately, I can't test any new code for a few days, so a patch that changes this, while trivial, may be bugged. Unless I get an ack from you, I'll send a timer which negates elsewhere in a day or so.
/alessandro
participants (3)
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Alessandro Rubini -
Alessandro Rubini -
Wolfgang Denk