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 <mjon...@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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