netdev - Re: [Bug] net/fec on i.MX28: promiscuous mode lost after reconnecting network cable

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Date:	Thu, 6 Mar 2014 11:43:22 -0600
From:	Frank Li <lznuaa@...il.com>
To:	Fabio Estevam <festevam@...il.com>
Cc:	Stefan Wahren <stefan.wahren@...e.com>,
	David Miller <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	linux-arm-kernel@...ts.arm.linux.org.uk,
	Shawn Guo <shawn.guo@...aro.org>,
	Fabio Estevam <fabio.estevam@...escale.com>,
	Frank Li <Frank.Li@...escale.com>,
	Duan Fugang-B38611 <B38611@...escale.com>,
	Sascha Hauer <kernel@...gutronix.de>
Subject: Re: [Bug] net/fec on i.MX28: promiscuous mode lost after reconnecting
 network cable

On Thu, Mar 6, 2014 at 4:30 AM, Fabio Estevam <festevam@...il.com> wrote:
> Adding some more folks on Cc.
>
> On Thu, Mar 6, 2014 at 6:29 AM, Stefan Wahren <stefan.wahren@...e.com> wrote:
>> Hello,
>>
>> i'm using a i.MX28 custom board (I2SE Duckbill) with 2 different Ethernet
>> interfaces. Both interfaces should be used as bridge using bridge utils. One
>> Ethernet interface is the buildin fec and the other is connect by spi. The
>> board runs under Linux mainline 3.10. But the following problem still occurs
>> on 3.14-rc4.
>>
>> Here is the problem, if i disconnect and reconnect the Ethernet cable on the
>> buildin fec (eth0), the bridge says the port comes up, but it doesn't work.
>> After that any traffic to the fec is okay, but traffic "through" the bridge
>> is lost. But i expect no traffic is lost, after reconnect the network cable.
>>
>> If i reset the board without disconnecting the cables, the traffic "through"
>> the bridge works. If i force the promiscuous mode on the fec (eth0) after
>> the reconnect, the bridge works too:
>>
>> ifconfig eth0 promisc
>>
>> After that, i made some research and probably found the cause of the
>> problem. In the case that the bridge works (link state connected since
>> reboot) the register HW_ENET_MAC_RCR of the i.MX28 returns 0x45EE011C
>> (PROM=1, promiscuous mode on). Then I disconnect the ethernet cable and
>> reconnect it. After that the register returns 0x45EE0114 (PROM=0,
>> promiscuous mode off) and the bridge doesn't work.
>>
>> Based on this information, i created a patch against Linux 3.10. I'm not
>> sure it's a good solution but it works. After a fec reset all register
>> values of HW_ENET_MAC_RCR must be restored, but fec_restart do not handle
>> them at all. So set_multicast_list is called after fec_restart to restore
>> the promiscuous mode of the fec.
>>
>> diff --git a/drivers/net/ethernet/freescale/fec_main.c
>> b/drivers/net/ethernet/freescale/fec_main.c
>> index d48099f..cb6b66e 100644
>> --- a/drivers/net/ethernet/freescale/fec_main.c
>> +++ b/drivers/net/ethernet/freescale/fec_main.c
>> @@ -1063,6 +1063,8 @@ static void fec_get_mac(struct net_device *ndev)
>>
>>  /*
>> ------------------------------------------------------------------------- */
>>
>> +static void set_multicast_list(struct net_device *ndev);
>> +
>>  /*
>>   * Phy section
>>   */
>> @@ -1093,8 +1095,10 @@ static void fec_enet_adjust_link(struct net_device
>> *ndev)
>>          }
>>
>>          /* if any of the above changed restart the FEC */
>> -        if (status_change)
>> +        if (status_change) {
>>              fec_restart(ndev, phy_dev->duplex);
>> +            set_multicast_list(ndev);
>> +        }
>>      } else {
>>          if (fep->link) {
>>              fec_stop(ndev);
>>
>> Is this solution correct?

There are many places to call fec_resart.
I suggest call set_multicase_list in fec_restart function.

>>
>> Do you need more information?
>>
>> Best regards
>> Stefan Wahren
>> --
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