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

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Date:	Thu, 6 Mar 2014 07:30:34 -0300
From:	Fabio Estevam <festevam@...il.com>
To:	Stefan Wahren <stefan.wahren@...e.com>
Cc:	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

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