[PATCH v2] net/fec_mpc52xx: Fix kernel panic on FEC error

[PATCH v2] net/fec_mpc52xx: Fix kernel panic on FEC error

[Grant Likely]

From: John Bonesio <bones@secretlab.ca>

The MDIO bus cannot be accessed at interrupt context, but on an FEC
error, the fec_mpc52xx driver reset function also tries to reset the
PHY.  Since the error is detected at IRQ context, and the PHY functions
try to sleep, the kernel ends up panicking.

Resetting the PHY on an FEC error isn't even necessary.  This patch
solves the problem by removing the PHY reset entirely.

Signed-off-by: John Bonesio <bones@secretlab.ca>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---

v2: fixed stupid misspelling of John's email address.  No changes to content.

 drivers/net/fec_mpc52xx.c |    6 ------
 1 files changed, 0 insertions(+), 6 deletions(-)

diff --git a/drivers/net/fec_mpc52xx.c b/drivers/net/fec_mpc52xx.c
index c40113f..66dace6 100644
--- a/drivers/net/fec_mpc52xx.c
+++ b/drivers/net/fec_mpc52xx.c
@@ -759,12 +759,6 @@ static void mpc52xx_fec_reset(struct net_device *dev)
 
 	mpc52xx_fec_hw_init(dev);
 
-	if (priv->phydev) {
-		phy_stop(priv->phydev);
-		phy_write(priv->phydev, MII_BMCR, BMCR_RESET);
-		phy_start(priv->phydev);
-	}
-
 	bcom_fec_rx_reset(priv->rx_dmatsk);
 	bcom_fec_tx_reset(priv->tx_dmatsk);

Re: [PATCH v2] net/fec_mpc52xx: Fix kernel panic on FEC error

[Wolfgang Grandegger]

Grant Likely wrote:
> From: John Bonesio <bones@secretlab.ca>
> 
> The MDIO bus cannot be accessed at interrupt context, but on an FEC
> error, the fec_mpc52xx driver reset function also tries to reset the
> PHY.  Since the error is detected at IRQ context, and the PHY functions
> try to sleep, the kernel ends up panicking.
> 
> Resetting the PHY on an FEC error isn't even necessary.  This patch
> solves the problem by removing the PHY reset entirely.

There is also no need to free and re-allocate the RX buffers in
mpc52xx_fec_reset().

Wolfgang.

Re: [PATCH v2] net/fec_mpc52xx: Fix kernel panic on FEC error

[Grant Likely]

On Wed, Oct 14, 2009 at 1:11 PM, Wolfgang Grandegger <wg@grandegger.com> wrote:
> Grant Likely wrote:
>> From: John Bonesio <bones@secretlab.ca>
>>
>> The MDIO bus cannot be accessed at interrupt context, but on an FEC
>> error, the fec_mpc52xx driver reset function also tries to reset the
>> PHY.  Since the error is detected at IRQ context, and the PHY functions
>> try to sleep, the kernel ends up panicking.
>>
>> Resetting the PHY on an FEC error isn't even necessary.  This patch
>> solves the problem by removing the PHY reset entirely.
>
> There is also no need to free and re-allocate the RX buffers in
> mpc52xx_fec_reset().

Write and test a patch for me!  :-)

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: [PATCH v2] net/fec_mpc52xx: Fix kernel panic on FEC error

[David Miller]

From: Grant Likely <grant.likely@secretlab.ca>
Date: Wed, 14 Oct 2009 11:43:43 -0600

> From: John Bonesio <bones@secretlab.ca>
> 
> The MDIO bus cannot be accessed at interrupt context, but on an FEC
> error, the fec_mpc52xx driver reset function also tries to reset the
> PHY.  Since the error is detected at IRQ context, and the PHY functions
> try to sleep, the kernel ends up panicking.
> 
> Resetting the PHY on an FEC error isn't even necessary.  This patch
> solves the problem by removing the PHY reset entirely.
> 
> Signed-off-by: John Bonesio <bones@secretlab.ca>
> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Applied, thanks.