netdev - Re: [PATCH] net/fec: infinite spin on sirq-net-tx on real-time

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Date:	Mon, 06 Feb 2012 14:39:59 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Hector Palacios <hector.palacios@...i.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
	"jgq516@...il.com" <jgq516@...il.com>,
	"tim.sander@....com" <tim.sander@....com>,
	"u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	Zeng Zhaoming <b32542@...escale.com>,
	Frank Li <Frank.Li@...escale.com>
Subject: Re: [PATCH] net/fec: infinite spin on sirq-net-tx on real-time

Le lundi 06 février 2012 à 08:25 -0500, Steven Rostedt a écrit :
> On Mon, 2012-02-06 at 12:03 +0100, Hector Palacios wrote:
> 
> > >>
> > >> @@ -530,6 +531,7 @@ fec_stop(struct net_device *ndev)
> > >>   	udelay(10);
> > >>   	writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);
> > >>   	writel(FEC_DEFAULT_IMASK, fep->hwp + FEC_IMASK);
> > >> +	fep->link = 0;
> > >
> > >
> > > Why not call netif_stop_queue(dev) here ?
> > >
> 
> > I'm no network driver expert so I'll leave it up to others to comment. I just forward 
> > ported a patch I came across in Freescale's BSP which solves the problem in mainline 
> > and in RT.
> 
> Hector,
> 
> Eric's suggestion may also work. Could your revert this patch and add
> the netif_stop_queue(dev) there, and see if it fixes the problems in
> both mainline and -rt?

Not sure it will be enough to call netif_stop_queue(dev) in fec_stop()

We probably need to start the device with its tx queue stopped, then
later when device is really ready wakeup the queue.



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