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 <[email protected]> Signed-off-by: Will Deacon <[email protected]> --- arch/openrisc/lib/delay.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/openrisc/lib/delay.c b/arch/openrisc/lib/delay.c index 0c12407..c330767 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); -- 1.7.4.1 _______________________________________________ Linux mailing list [email protected] http://lists.openrisc.net/listinfo/linux
