diff options
| author | Mischa Jonker <mjonker@synopsys.com> | 2013-08-30 13:56:25 +0400 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2013-09-05 09:01:12 +0400 |
| commit | 7efd0da2d17360e1cef91507dbe619db0ee2c691 (patch) | |
| tree | 368a10f49fae6386d201154b6a628cf7b4c01e67 | |
| parent | 8508d5653f4ca25cd13f87340121afdfed448e1b (diff) | |
| download | linux-7efd0da2d17360e1cef91507dbe619db0ee2c691.tar.xz | |
ARC: Fix __udelay calculation
Cast usecs to u64, 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, causing a "DMA initialization error" in the stmmac Ethernet
driver, due to a premature timeout.
Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
| -rw-r--r-- | arch/arc/include/asm/delay.h | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/arc/include/asm/delay.h b/arch/arc/include/asm/delay.h index 442ce5d0f709..43de30256981 100644 --- a/arch/arc/include/asm/delay.h +++ b/arch/arc/include/asm/delay.h @@ -53,11 +53,10 @@ static inline void __udelay(unsigned long usecs) { unsigned long loops; - /* (long long) cast ensures 64 bit MPY - real or emulated + /* (u64) 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 = ((u64) usecs * 4295 * HZ * loops_per_jiffy) >> 32; __delay(loops); } |