netdev - [PATCH v2 net] gianfar: Fix boot hangs while bringing up gianfar ethernet

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Date:	Mon, 9 Feb 2009 20:40:27 +0100
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Jeff Garzik <jeff@...zik.org>, David Miller <davem@...emloft.net>
Cc:	Ira Snyder <iws@...o.caltech.edu>,
	Peter Korsgaard <jacmet@...site.dk>,
	Dai Haruki <dai.haruki@...escale.com>,
	Andy Fleming <afleming@...escale.com>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v2 net] gianfar: Fix boot hangs while bringing up gianfar
	ethernet

> PS#2: Andy, this changelog is really a lot harder than the patch...

Hmm...

-------------------> (take 2 - signed-off fix only)

gianfar: Fix boot hangs while bringing up gianfar ethernet

Ira Snyder found that commit 8c7396aebb68994c0519e438eecdf4d5fa9c7844
"gianfar: Merge Tx and Rx interrupt for scheduling clean up ring" can
cause hangs. It's because there was removed clearing of interrupts in
gfar_schedule_cleanup() (which is called by an interrupt handler) in
case when netif scheduling has been disabled. This patch brings back
this action and a comment.

Reported-by: Ira Snyder <iws@...o.caltech.edu>
Reported-by: Peter Korsgaard <jacmet@...site.dk>
Bisected-by: Ira Snyder <iws@...o.caltech.edu>
Tested-by: Peter Korsgaard <jacmet@...site.dk>
Tested-by: Ira Snyder <iws@...o.caltech.edu>
Signed-off-by: Jarek Poplawski <jarkao2@...il.com>

---

 drivers/net/gianfar.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index acae2d8..9b12a13 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -1629,6 +1629,12 @@ static void gfar_schedule_cleanup(struct net_device *dev)
 	if (netif_rx_schedule_prep(&priv->napi)) {
 		gfar_write(&priv->regs->imask, IMASK_RTX_DISABLED);
 		__netif_rx_schedule(&priv->napi);
+	} else {
+		/*
+		 * Clear IEVENT, so interrupts aren't called again
+		 * because of the packets that have already arrived.
+		 */
+		gfar_write(&priv->regs->ievent, IEVENT_RTX_MASK);
 	}
 
 	spin_unlock(&priv->rxlock);
--
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