Messages in this thread Patch in this message | | | From | Mischa Jonker <> | Subject | [PATCH] ARC: Fix __udelay parentheses | Date | Wed, 28 Aug 2013 20:29:48 +0200 |
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Make sure that usecs is casted to long long, to ensure that the (usecs * 4295 * HZ) multiplication is 64 bit.
Initially, the (usecs * 4295 * HZ) part was done as a 32 bit multiplication, with the result casted to 64 bit. This led to some bits falling off.
Signed-off-by: Mischa Jonker <mjonker@synopsys.com> --- arch/arc/include/asm/delay.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arc/include/asm/delay.h b/arch/arc/include/asm/delay.h index 442ce5d..8d35fe1 100644 --- a/arch/arc/include/asm/delay.h +++ b/arch/arc/include/asm/delay.h @@ -56,8 +56,8 @@ static inline void __udelay(unsigned long usecs) /* (long long) cast ensures 64 bit MPY - real or emulated * HZ * 4295 is pre-evaluated by gcc - hence only 2 mpy ops */ - loops = ((long long)(usecs * 4295 * HZ) * - (long long)(loops_per_jiffy)) >> 32; + loops = (((long long) usecs) * 4295 * HZ * + (long long) loops_per_jiffy) >> 32; __delay(loops); } -- 1.7.9.5
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