netdev - Re: [PATCH] net: dsa: mv88e6xxx: rework in-chip bridging

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Date:   Sun, 8 Oct 2017 21:00:08 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Greg Ungerer <gerg@...ux-m68k.org>,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH] net: dsa: mv88e6xxx: rework in-chip bridging

Le 10/08/17 à 20:23, Greg Ungerer a écrit :
> Hi Florian,
> 
> On 07/10/17 13:04, Florian Fainelli wrote:
>> Le 10/03/17 à 23:20, Greg Ungerer a écrit :
>>> On Wed, Mar 29, 2017 at 04:30:16PM -0400, Vivien Didelot wrote:
>>>> All ports -- internal and external, for chips featuring a PVT -- have a
>>>> mask restricting to which internal ports a frame is allowed to egress.
>>>>
>>>> Now that DSA exposes the number of ports and their bridge devices, it is
>>>> possible to extract the code generating the VLAN map and make it generic
>>>> so that it can be shared later with the cross-chip bridging code.
>>>
>>> This patch changes the behavior of interfaces on startup if they are
>>> not part of a bridge.
>>>
>>> I have a board with a Marvell 6350 switch with a device tree that sets
>>> up the 5 ports as lan1, lan2, lan3, lan4, wan. With kernels before
>>> this patch (so linux-4.12 and older) after system startup I could do:
>>>
>>>   ifconfig lan1 192.168.0.1
>>>
>>> And then ping out that interface with no problems.
>>>
>>> After this patch is applied (effects linux-4.13 and newer) then the
>>> ping fails:
>>>
>>>   PING 192.168.0.22 (192.168.0.22) 56(84) bytes of data.
>>>   From 192.168.0.1 icmp_seq=1 Destination Host Unreachable
>>>   From 192.168.0.1 icmp_seq=2 Destination Host Unreachable
>>>   From 192.168.0.1 icmp_seq=3 Destination Host Unreachable
>>>
>>> If I incorporate an interface into a bridge then it all works ok.
>>> So simply:
>>>
>>>   brctl addbr br0
>>>   brctl addif br0 lan1
>>>   ifconfig lan1 up
>>>   ifconfig br0 192.168.0.1
>>>
>>> Then pings out work as expected. And if I now remove that lan1
>>> interface from the bridge and use it alone again then it will
>>> now work ok:
>>>
>>>   ifconfig br0 down
>>>   brctl delif br0 lan1
>>>   ifconfig lan1 192.168.0.1
>>>
>>> And that now pings ok.
>>>
>>> I fixed this with the attached patch. It is probably not the correct
>>> approach, but it does restore the older behavior.
>>>
>>> What do you think?
>>
>> This is strange, the dsa_switch_tree and its associated dsa_switch
>> instances should be fully setup by the time ops->setup() is running in
>> your driver but your patch suggests this may not be happening?
> 
> That is what I am seeing, yep.
> 
> 
>> Are you using the new style Device Tree binding or the old style Device
>> Tree binding out of curiosity?
> 
> This is my device tree fragment for the switch:
> 
>         dsa@0 {
>                 compatible = "marvell,dsa";
>                 #address-cells = <2>;
>                 #size-cells = <0>;
> 
>                 dsa,ethernet = <&eth0>;
>                 dsa,mii-bus = <&mdio>;
> 
>                 switch@0 {
>                         #address-cells = <1>;
>                         #size-cells = <0>;
>                         reg = <0x11 0>;
> 
>                         port@0 {
>                                 reg = <0>;
>                                 label = "lan1";
>                         };
>                         port@1 {
>                                 reg = <1>;
>                                 label = "lan2";
>                         };
>                         port@2 {
>                                 reg = <2>;
>                                 label = "lan3";
>                         };
>                         port@3 {
>                                 reg = <3>;
>                                 label = "lan4";
>                         };
>                         port@4 {
>                                 reg = <4>;
>                                 label = "wan";
>                         };
>                         port@5 {
>                                 reg = <5>;
>                                 label = "cpu";
>                         };
>                 };
>          };
> 
> The board I am using is based around an Marvell Armada 370. This device tree
> setup looks pretty similar to the other Marvell boards using marvell,dsa.

This is the old Device Tree binding which goes through an unfortunately
different code path while initializing all the dsa_switch_tree and
dsa_switch structures, while we should definitively look into fixing
this, would you mind trying to update your board using something similar
to this commit:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4cb2ec8cad8c82cd7cfd19edcacd846861d6e703

This would make you go through net/dsa/dsa2.c which is what most of us
usually test. In the meantime we should probably start issuing warning
messages when people use the old Device Tree binding to encourage them
to migrate other.
-- 
Florian