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

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Message-ID: <f7c8b4dab2114552b919310c2a5bb444@BLUPR03MB373.namprd03.prod.outlook.com>
Date:	Fri, 7 Mar 2014 02:10:01 +0000
From:	"fugang.duan@...escale.com" <fugang.duan@...escale.com>
To:	Frank Li <lznuaa@...il.com>, 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" 
	<linux-arm-kernel@...ts.arm.linux.org.uk>,
	Shawn Guo <shawn.guo@...aro.org>,
	"Fabio.Estevam@...escale.com" <Fabio.Estevam@...escale.com>,
	"Frank.Li@...escale.com" <Frank.Li@...escale.com>,
	Sascha Hauer <kernel@...gutronix.de>
Subject: RE: [Bug] net/fec on i.MX28: promiscuous mode lost after
 reconnecting network cable

From: Frank Li <lznuaa@...il.com>
Data: Friday, March 07, 2014 1:43 AM

>To: Fabio Estevam
>Cc: Stefan Wahren; David Miller; netdev@...r.kernel.org; linux-arm-
>kernel@...ts.arm.linux.org.uk; Shawn Guo; Estevam Fabio-R49496; Li Frank-B20596;
>Duan Fugang-B38611; Sascha Hauer
>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.
>
Yes, we had called set_multicase_list() in fec_restart() function. 
The patch is redundant.

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