This is a note to let you know that I've just added the patch titled
ARC: Fix __udelay calculation
to the 3.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arc-fix-__udelay-calculation.patch
and it can be found in the queue-3.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 7efd0da2d17360e1cef91507dbe619db0ee2c691 Mon Sep 17 00:00:00 2001
From: Mischa Jonker <[email protected]>
Date: Fri, 30 Aug 2013 11:56:25 +0200
Subject: ARC: Fix __udelay calculation
From: Mischa Jonker <[email protected]>
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 <[email protected]>
Signed-off-by: Vineet Gupta <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/arc/include/asm/delay.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/arch/arc/include/asm/delay.h
+++ b/arch/arc/include/asm/delay.h
@@ -53,11 +53,10 @@ static inline void __udelay(unsigned lon
{
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);
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.11/arc-handle-zero-overhead-loop-in-unaligned-access-handler.patch
queue-3.11/arc-fix-__udelay-calculation.patch
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