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authorMischa Jonker <mjonker@synopsys.com>2013-08-30 11:56:25 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-10-18 07:45:45 -0700
commit8036c31c84117707d4132cd199d997d7ed41427c (patch)
tree33c8a035061278ccabc7196be5ccffbebd4811cd /arch
parent98f745546bd27e54fe0bed1e9c900301428de9d5 (diff)
downloadvexpress-lsk-8036c31c84117707d4132cd199d997d7ed41427c.tar.gz
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')
-rw-r--r--arch/arc/include/asm/delay.h5
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);
}