netdev - Re: b44: Reset due to FIFO overflow.

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Message-ID: <1277716394.4235.235.camel@edumazet-laptop>
Date:	Mon, 28 Jun 2010 11:13:14 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	James Courtier-Dutton <james.dutton@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: b44: Reset due to FIFO overflow.

Le lundi 28 juin 2010 à 08:41 +0100, James Courtier-Dutton a écrit :
> Hi,
> 
> Reference:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/279102
> 
> I can see this bug and can reproduce it 100% on demand.
> The problem seems to be that when the b44 has a incoming FIFO buffer
> overflow, it resets the entire card, dis-associates with the access
> point and therefore takes some time before it can pass traffic again.
> Can anyone point me to some code that would just recover the FIFO
> instead of reset the entire card?
> 
> I am a kernel developer, but I don't have any data sheets on this card
> so was hoping someone with more knowledge of its workings, could help
> me.
> 
> I can then test it, and see if it is a good fix or not.
> 

Hi

Problem is we dont know if a Receive Fifo overflow is a minor or major
indication from b44 chip.

A minor indication would be : Chip tells us one or more frame were lost.
No special action needed from driver.

A major indication (as of current implemented in b44 driver) is :
I am completely out of order and need a reset. Please do it.

Patch to switch from major to minor indication is easy, but we dont know
if its valid or not.

diff --git a/drivers/net/b44.h b/drivers/net/b44.h
index e1905a4..514dc3a 100644
--- a/drivers/net/b44.h
+++ b/drivers/net/b44.h
@@ -42,7 +42,7 @@
 #define  ISTAT_EMAC		0x04000000 /* EMAC Interrupt */
 #define  ISTAT_MII_WRITE	0x08000000 /* MII Write Interrupt */
 #define  ISTAT_MII_READ		0x10000000 /* MII Read Interrupt */
-#define  ISTAT_ERRORS (ISTAT_DSCE|ISTAT_DATAE|ISTAT_DPE|ISTAT_RDU|ISTAT_RFO|ISTAT_TFU)
+#define  ISTAT_ERRORS (ISTAT_DSCE|ISTAT_DATAE|ISTAT_DPE|ISTAT_RDU|ISTAT_TFU)
 #define B44_IMASK	0x0024UL /* Interrupt Mask */
 #define  IMASK_DEF		(ISTAT_ERRORS | ISTAT_TO | ISTAT_RX | ISTAT_TX)
 #define B44_GPTIMER	0x0028UL /* General Purpose Timer */


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