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| author | Mischa Jonker <mjonker@synopsys.com> | 2013-08-30 11:56:25 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-18 07:45:45 -0700 |
| commit | 8036c31c84117707d4132cd199d997d7ed41427c (patch) | |
| tree | 33c8a035061278ccabc7196be5ccffbebd4811cd /arch/arc | |
| parent | 98f745546bd27e54fe0bed1e9c900301428de9d5 (diff) | |
| download | linux-3.10-8036c31c84117707d4132cd199d997d7ed41427c.tar.gz linux-3.10-8036c31c84117707d4132cd199d997d7ed41427c.tar.bz2 linux-3.10-8036c31c84117707d4132cd199d997d7ed41427c.zip | |
ARC: Fix __udelay calculation
commit 7efd0da2d17360e1cef91507dbe619db0ee2c691 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arc')
| -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 442ce5d0f70..43de3025698 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); } |