linux-kernel - Re: [PATCH net-next v3 4/5] net: dsa: mv88e6xxx: Add support for bridge port locked mode

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Date:   Mon, 21 Feb 2022 15:05:58 +0100
From:   Hans Schultz <schultz.hans@...il.com>
To:     Ido Schimmel <idosch@...sch.org>,
        Vladimir Oltean <olteanv@...il.com>
Cc:     Hans Schultz <schultz.hans@...il.com>, davem@...emloft.net,
        kuba@...nel.org, netdev@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Shuah Khan <shuah@...nel.org>,
        Stephen Suryaputra <ssuryaextr@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Ido Schimmel <idosch@...dia.com>,
        Petr Machata <petrm@...dia.com>,
        Amit Cohen <amcohen@...dia.com>,
        Po-Hsu Lin <po-hsu.lin@...onical.com>,
        Baowen Zheng <baowen.zheng@...igine.com>,
        linux-kernel@...r.kernel.org, bridge@...ts.linux-foundation.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next v3 4/5] net: dsa: mv88e6xxx: Add support for
 bridge port locked mode

On sön, feb 20, 2022 at 11:21, Ido Schimmel <idosch@...sch.org> wrote:
> On Sat, Feb 19, 2022 at 12:00:34PM +0200, Vladimir Oltean wrote:
>> On Fri, Feb 18, 2022 at 04:51:47PM +0100, Hans Schultz wrote:
>> > diff --git a/drivers/net/dsa/mv88e6xxx/port.c b/drivers/net/dsa/mv88e6xxx/port.c
>> > index ab41619a809b..46b7381899a0 100644
>> > --- a/drivers/net/dsa/mv88e6xxx/port.c
>> > +++ b/drivers/net/dsa/mv88e6xxx/port.c
>> > @@ -1234,6 +1234,39 @@ int mv88e6xxx_port_set_mirror(struct mv88e6xxx_chip *chip, int port,
>> >  	return err;
>> >  }
>> >  
>> > +int mv88e6xxx_port_set_lock(struct mv88e6xxx_chip *chip, int port,
>> > +			    bool locked)
>> > +{
>> > +	u16 reg;
>> > +	int err;
>> > +
>> > +	err = mv88e6xxx_port_read(chip, port, MV88E6XXX_PORT_CTL0, &reg);
>> > +	if (err)
>> > +		return err;
>> > +
>> > +	reg &= ~MV88E6XXX_PORT_CTL0_SA_FILT_MASK;
>> > +	if (locked)
>> > +		reg |= MV88E6XXX_PORT_CTL0_SA_FILT_DROP_ON_LOCK;
>> > +
>> > +	err = mv88e6xxx_port_write(chip, port, MV88E6XXX_PORT_CTL0, reg);
>> > +	if (err)
>> > +		return err;
>> > +
>> > +	err = mv88e6xxx_port_read(chip, port, MV88E6XXX_PORT_ASSOC_VECTOR, &reg);
>> > +	if (err)
>> > +		return err;
>> > +
>> > +	reg &= ~MV88E6XXX_PORT_ASSOC_VECTOR_LOCKED_PORT;
>> > +	if (locked)
>> > +		reg |= MV88E6XXX_PORT_ASSOC_VECTOR_LOCKED_PORT;
>> > +
>> > +	err = mv88e6xxx_port_write(chip, port, MV88E6XXX_PORT_ASSOC_VECTOR, reg);
>> 
>> 	return mv88e6xxx_port_write(...);
>
> Not familiar with mv88e6xxx, but shouldn't there be a rollback of
> previous operations? Specifically mv88e6xxx_port_write()
>

If a register write function fails, I don't think that it would make
sense to try and resolve the situation by additional register write
calls (rollback).

>> 
>> > +	if (err)
>> > +		return err;
>> > +
>> > +	return 0;
>> > +}