[PATCH] ll_temac: Reset dma descriptors on ndo_open

[PATCH] ll_temac: Reset dma descriptors on ndo_open

[Ricardo Ribalda Delgado]

The dma descriptors are only initialized on the probe function.

If a packet is on the buffer when temac_stop is called, the dma
descriptors can be left on a incorrect status where no other package can
be sent.

So an interface could be left in an usable state after ifdow/ifup.

This patch makes sure that the descriptors are in a proper status when
the device is started.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---
 drivers/net/ethernet/xilinx/ll_temac_main.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
index b88121f..8bae87f 100644
--- a/drivers/net/ethernet/xilinx/ll_temac_main.c
+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
@@ -229,6 +229,25 @@ static void temac_dma_bd_release(struct net_device *ndev)
 }
 
 /**
+ * temac_dma_bd_reset - Reset buffer descriptor rings
+ */
+static void temac_dma_bd_reset(struct net_device *ndev)
+{
+	struct temac_local *lp = netdev_priv(ndev);
+	int i;
+
+	for (i = 0; i < TX_BD_NUM; i++)
+		lp->tx_bd_v[i].app0 = 0;
+
+	lp->tx_bd_ci = 0;
+	lp->tx_bd_next = 0;
+	lp->tx_bd_tail = 0;
+	lp->rx_bd_ci = 0;
+
+	return;
+}
+
+/**
  * temac_dma_bd_init - Setup buffer descriptor rings
  */
 static int temac_dma_bd_init(struct net_device *ndev)
@@ -864,6 +883,8 @@ static int temac_open(struct net_device *ndev)
 	if (rc)
 		goto err_rx_irq;
 
+	temac_dma_bd_reset(ndev);
+
 	return 0;
 
  err_rx_irq:
-- 
1.8.4.rc3

Re: [PATCH] ll_temac: Reset dma descriptors on ndo_open

[David Miller]

From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Date: Fri, 27 Sep 2013 13:24:28 +0200

> The dma descriptors are only initialized on the probe function.
> 
> If a packet is on the buffer when temac_stop is called, the dma
> descriptors can be left on a incorrect status where no other package can
> be sent.
> 
> So an interface could be left in an usable state after ifdow/ifup.
> 
> This patch makes sure that the descriptors are in a proper status when
> the device is started.
> 
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>

This analysis is not correct.

In the current driver, the descriptors are allocated and initialized
in the open function, not the probe function.

I'm not applying this patch.

Re: [PATCH] ll_temac: Reset dma descriptors on ndo_open

[Ricardo Ribalda Delgado]

Hello David

lp->tx_bd_ci, lp->tx_bd_next...  are only initialized to zero on
temac_of_probe (inside  alloc_etherdev).  Those vars are used to index
the dma descriptors.

The initialization of  lp->tx_bd_v[i].app0 = 0; is redundant, because
it is already done on dma_zalloc_coherent in temac_dma_bd_init called
on open.

What if I move
       lp->tx_bd_ci = 0;
       lp->tx_bd_next = 0;
       lp->tx_bd_tail = 0;
       lp->rx_bd_ci = 0;

to temac_dma_bd_init? Will this be more correct?

Without this patch a script like these kills the card in 1-10 iterations:


ifdown eth0
ifdown eth1
while true

do
ifconfig eth1 10.100.10.100
udhcpc -i eth0
ping 192.168.2.1 -c 5 || break
ifconfig eth0 down


ifconfig eth0 10.100.10.100
udhcpc -i eth1
ping 192.168.2.1 -c 5 || break
ifconfig eth1 down

done


Regards

On Tue, Oct 1, 2013 at 6:21 AM, David Miller <davem@davemloft.net> wrote:
> From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> Date: Fri, 27 Sep 2013 13:24:28 +0200
>
>> The dma descriptors are only initialized on the probe function.
>>
>> If a packet is on the buffer when temac_stop is called, the dma
>> descriptors can be left on a incorrect status where no other package can
>> be sent.
>>
>> So an interface could be left in an usable state after ifdow/ifup.
>>
>> This patch makes sure that the descriptors are in a proper status when
>> the device is started.
>>
>> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
>
> This analysis is not correct.
>
> In the current driver, the descriptors are allocated and initialized
> in the open function, not the probe function.
>
> I'm not applying this patch.



-- 
Ricardo Ribalda

Re: [PATCH] ll_temac: Reset dma descriptors on ndo_open

[David Miller]

From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Date: Tue, 1 Oct 2013 07:46:31 +0200

> What if I move
>        lp->tx_bd_ci = 0;
>        lp->tx_bd_next = 0;
>        lp->tx_bd_tail = 0;
>        lp->rx_bd_ci = 0;
> 
> to temac_dma_bd_init? Will this be more correct?

Yes, that would be a lot better.

Re: [PATCH] ll_temac: Reset dma descriptors on ndo_open

[Ricardo Ribalda Delgado]

Just send a v2 of the patch

http://patchwork.ozlabs.org/patch/279339/

Thanks!

On Tue, Oct 1, 2013 at 8:01 AM, David Miller <davem@davemloft.net> wrote:
> From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> Date: Tue, 1 Oct 2013 07:46:31 +0200
>
>> What if I move
>>        lp->tx_bd_ci = 0;
>>        lp->tx_bd_next = 0;
>>        lp->tx_bd_tail = 0;
>>        lp->rx_bd_ci = 0;
>>
>> to temac_dma_bd_init? Will this be more correct?
>
> Yes, that would be a lot better.



-- 
Ricardo Ribalda