On Fri, Aug 04, 2006 at 12:39:12PM +0200, Michael Buesch wrote:
> On Friday 04 August 2006 08:56, Willy Tarreau wrote:
> > On Thu, Aug 03, 2006 at 06:56:15PM +0100, Alan Cox wrote:
> > > Ar Iau, 2006-08-03 am 19:53 +0300, ysgrifennodd Jukka Partanen:
> > > > AVM C4 ISDN NIC: Add three memory barriers, taken from 2.6.7,
> > > > (they are there in 2.6.17.7 too), to fix module initialization
> > > > problems appearing with at least some newer Celerons and
> > > > Pentium III.
> > >
> > > Should be using cpu_relax() I think. Its a polled busy loop so you want
> > > other CPU threads to run if possible.
(...)
> cpu_relax() implies a memory barrier.
Ok, here's the updated patch for 2.6 using cpu_relax() instead of
mb(), as suggested by Alan and Michael.
Regards,
Willy
> Greetings Michael.
>From b76136dc1ac989081933d28ec958ecdd32d368e4 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <[email protected]>
Date: Fri, 4 Aug 2006 22:11:23 +0200
Subject: [PATCH] AVM C4 ISDN card : use cpu_relax() in busy loops
As suggested by Alan, use cpu_relax() in 3 busy loops : "It's a
polled busy loop so you want other CPU threads to run if possible".
Signed-off-by: Willy Tarreau <[email protected]>
---
drivers/isdn/hardware/avm/c4.c | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/isdn/hardware/avm/c4.c b/drivers/isdn/hardware/avm/c4.c
index f7253b2..8149dce 100644
--- a/drivers/isdn/hardware/avm/c4.c
+++ b/drivers/isdn/hardware/avm/c4.c
@@ -22,6 +22,7 @@ #include <linux/capi.h>
#include <linux/kernelcapi.h>
#include <linux/init.h>
#include <asm/io.h>
+#include <asm/processor.h>
#include <asm/uaccess.h>
#include <linux/netdevice.h>
#include <linux/isdn/capicmd.h>
@@ -149,7 +150,7 @@ static inline int wait_for_doorbell(avmc
while (c4inmeml(card->mbase+DOORBELL) != 0xffffffff) {
if (!time_before(jiffies, stop))
return -1;
- mb();
+ cpu_relax();
}
return 0;
}
@@ -302,7 +303,7 @@ static void c4_reset(avmcard *card)
if (!time_before(jiffies, stop))
return;
c4outmeml(card->mbase+DOORBELL, DBELL_ADDR);
- mb();
+ cpu_relax();
}
c4_poke(card, DC21285_ARMCSR_BASE + CHAN_1_CONTROL, 0);
@@ -326,7 +327,7 @@ static int c4_detect(avmcard *card)
if (!time_before(jiffies, stop))
return 2;
c4outmeml(card->mbase+DOORBELL, DBELL_ADDR);
- mb();
+ cpu_relax();
}
c4_poke(card, DC21285_ARMCSR_BASE + CHAN_1_CONTROL, 0);
--
1.4.1
-
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