linux-kernel - Re: [PATCH] de2104x: remove BUG

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Date:	Tue, 25 Mar 2008 00:02:19 +0100
From:	Ondrej Zary <linux@...nbow-software.org>
To:	Grant Grundler <grundler@...isc-linux.org>
Cc:	Jeff Garzik <jgarzik@...ox.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	netdev@...r.kernel.org
Subject: Re: [PATCH] de2104x: remove BUG_ON() when changing media type

On Monday 24 March 2008 03:45:14 Grant Grundler wrote:
> On Mon, Feb 25, 2008 at 12:52:17PM -0500, Jeff Garzik wrote:
> > Ondrej Zary wrote:
> >> When the chip dies (probably because of a bug somewhere in the driver),
> >> de_stop_rxtx() fails and changing the media type crashes the whole
> >> machine. Replace BUG_ON() in de_set_media() with a warning.
> >> Signed-off-by: Ondrej Zary <linux@...nbow-software.org>
> >> --- linux-2.6.24-orig/drivers/net/tulip/de2104x.c	2008-02-25
> >> 18:27:34.000000000 +0100
> >> +++ linux-2.6.24-pentium/drivers/net/tulip/de2104x.c	2008-02-25
> >> 18:34:56.000000000 +0100
> >> @@ -910,7 +910,8 @@
> >>  	unsigned media = de->media_type;
> >>  	u32 macmode = dr32(MacMode);
> >>  -	BUG_ON(de_is_running(de));
> >> +	if (de_is_running(de))
> >> +		printk(KERN_WARNING "%s: chip is running while changing media!\n",
> >> de->dev->name);
> >
> > Certainly a sane improvement...
>
> Jeff,
> The above patch was applied and fixes the 'panic' part of the problme.
> Can you take a look at this patch to fix the "chip is still running"
> part of this bug?

I'll test it but I doubt that it fixes the problem. IIRC, I tried something 
like that. Even tried resetting the chip multiple times when this problem 
appears but everything failed.


>
> BTW, I inherited a bug report for the same symptom:
>     http://bugzilla.kernel.org/show_bug.cgi?id=3156
>
> thanks,
> grant
>
> Signed-off-by: Grant Grundler
>
> --- linux-2.6.23/drivers/net/tulip/de2104x.c	2007-10-09 13:31:38.000000000
> -0700 +++ linux-2.6.23/drivers/net/tulip/de2104x.c-ggg	2007-11-02
> 23:24:46.000000000 -0700 @@ -842,7 +842,7 @@
>  static void de_stop_rxtx (struct de_private *de)
>  {
>  	u32 macmode;
> -	unsigned int work = 1000;
> +	unsigned int i = 1300/100;
>
>  	macmode = dr32(MacMode);
>  	if (macmode & RxTx) {
> @@ -850,10 +850,14 @@
>  		dr32(MacMode);
>  	}
>
> -	while (--work > 0) {
> +	/* wait until in-flight frame completes.
> +	 * Max time @ 10BT: 1500*8b/10Mbps == 1200us (+ 100us margin)
> +	 * Typically expect this loop to end in < 50 us on 100BT.
> +	 */
> +	while (--i) {
>  		if (!de_is_running(de))
>  			return;
> -		cpu_relax();
> +		udelay(100);
>  	}
>
>  	printk(KERN_WARNING "%s: timeout expired stopping DMA\n", de->dev->name);



-- 
Ondrej Zary
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