netdev - Re: [PATCH net-next 6/6] net: dsa: tag_8021q: Restore bridge pvid when enabling vlan

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Message-ID: <9a74874b-a932-f0f9-510d-687e4c9353d7@gmail.com>
Date:   Tue, 20 Aug 2019 10:36:38 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Vivien Didelot <vivien.didelot@...il.com>,
        Andrew Lunn <andrew@...n.ch>, Ido Schimmel <idosch@...sch.org>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        nikolay@...ulusnetworks.com,
        "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 6/6] net: dsa: tag_8021q: Restore bridge pvid
 when enabling vlan_filtering

On 8/20/19 3:28 AM, Vladimir Oltean wrote:
> Hi Florian,
> 
> On Tue, 20 Aug 2019 at 06:33, Florian Fainelli <f.fainelli@...il.com> wrote:
>>
>>
>>
>> On 8/19/2019 5:00 PM, Vladimir Oltean wrote:
>>> The bridge core assumes that enabling/disabling vlan_filtering will
>>> translate into the simple toggling of a flag for switchdev drivers.
>>>
>>> That is clearly not the case for sja1105, which alters the VLAN table
>>> and the pvids in order to obtain port separation in standalone mode.
>>>
>>> So, since the bridge will not call any vlan operation through switchdev
>>> after enabling vlan_filtering, we need to ensure we're in a functional
>>> state ourselves.
>>>
>>> Hence read the pvid that the bridge is aware of, and program that into
>>> our ports.
>>
>> That is arguably applicable with DSA at large and not just specifically
>> for tag_8021q.c no? Is there a reason why you are not seeking to solve
>> this on a more global scale?
>>
> 
> Perhaps because I don't have a good feel for what are other DSA
> drivers' struggles with restoring the pvid, even after re-reading the
> "What to do when a bridge port gets its pvid deleted?" thread.
> I understand b53 has a similar need, and for that purpose maybe you
> can EXPORT_SYMBOL_GPL(dsa_port_restore_pvid) and use it, but
> otherwise, what is the more global scale?

I was just referring to all DSA drivers, not just tag_8021q.c which is,
so far a very narrow user base. I don't have a strong feeling against
calling a helper function versus the core DSA layer doing this for you,
but clearly this is something that should plague all drivers, not just
sja1105, even if the effects of not restoring the PVID there may be more
"catastrophic".
-- 
Florian