From 807607f79b9d0ed81561746e4e1121905e75cf0f Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 7 Aug 2012 17:59:54 +0100 Subject: [PATCH] openrisc: delay: fix handling of counter overflow If the counter overflows during a __delay operation, we will exit the loop prematurely. For example, calling __delay(0x100) with the counter at 0xffffff00 gives us a target of 0x0. The unsigned comparison in the while loop will likely be false on the first iteration (if the counter is now anything other than 0) and we will return early. This patch fixes the problem by comparing deltas in the loop rather than absolute values. Cc: Jon Masters Signed-off-by: Will Deacon Signed-off-by: Jonas Bonn --- arch/openrisc/lib/delay.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/openrisc/lib/delay.c b/arch/openrisc/lib/delay.c index 0c12407d3d5c..c330767c9217 100644 --- a/arch/openrisc/lib/delay.c +++ b/arch/openrisc/lib/delay.c @@ -30,9 +30,9 @@ int __devinit read_current_timer(unsigned long *timer_value) void __delay(unsigned long cycles) { - cycles_t target = get_cycles() + cycles; + cycles_t start = get_cycles(); - while (get_cycles() < target) + while ((get_cycles() - start) < cycles) cpu_relax(); } EXPORT_SYMBOL(__delay);