Messages in this thread Patch in this message | | | Date | Fri, 4 Aug 2006 22:14:29 +0200 | From | Willy Tarreau <> | Subject | Re: [PATCH 2.4.32] Fix AVM C4 ISDN card init problems with newer CPUs |
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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 <w@1wt.eu> 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 <w@1wt.eu> --- 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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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