linux-kernel - Re: [PATCH net-next v3 1/3] net: dsa: rzn1-a5psw: use a5psw_reg

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Message-ID: <20230209094006.66ce1409@fixe.home>
Date:   Thu, 9 Feb 2023 09:40:06 +0100
From:   Clément Léger <clement.leger@...tlin.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Herve Codina <herve.codina@...tlin.com>,
        Miquèl Raynal <miquel.raynal@...tlin.com>,
        Milan Stevanovic <milan.stevanovic@...com>,
        Jimmy Lalande <jimmy.lalande@...com>,
        Pascal Eberhard <pascal.eberhard@...com>,
        Arun Ramadoss <Arun.Ramadoss@...rochip.com>,
        linux-renesas-soc@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 1/3] net: dsa: rzn1-a5psw: use
 a5psw_reg_rmw() to modify flooding resolution

Le Wed, 8 Feb 2023 23:37:57 +0200,
Vladimir Oltean <olteanv@...il.com> a écrit :

> On Wed, Feb 08, 2023 at 05:17:47PM +0100, Clément Léger wrote:
> > .port_bridge_flags will be added and allows to modify the flood mask
> > independently for each port. Keeping the existing bridged_ports write
> > in a5psw_flooding_set_resolution() would potentially messed up this.
> > Use a read-modify-write to set that value and move bridged_ports
> > handling in bridge_port_join/leave.
> > 
> > Signed-off-by: Clément Léger <clement.leger@...tlin.com>
> > ---
> >  drivers/net/dsa/rzn1_a5psw.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/net/dsa/rzn1_a5psw.c b/drivers/net/dsa/rzn1_a5psw.c
> > index 919027cf2012..8b7d4a371f8b 100644
> > --- a/drivers/net/dsa/rzn1_a5psw.c
> > +++ b/drivers/net/dsa/rzn1_a5psw.c
> > @@ -299,13 +299,9 @@ static void a5psw_flooding_set_resolution(struct a5psw *a5psw, int port,
> >  			A5PSW_MCAST_DEF_MASK};
> >  	int i;
> >  
> > -	if (set)
> > -		a5psw->bridged_ports |= BIT(port);
> > -	else
> > -		a5psw->bridged_ports &= ~BIT(port);
> > -
> >  	for (i = 0; i < ARRAY_SIZE(offsets); i++)
> > -		a5psw_reg_writel(a5psw, offsets[i], a5psw->bridged_ports);
> > +		a5psw_reg_rmw(a5psw, offsets[i], BIT(port),
> > +			      set ? BIT(port) : 0);
> >  }
> >  
> >  static int a5psw_port_bridge_join(struct dsa_switch *ds, int port,
> > @@ -326,6 +322,8 @@ static int a5psw_port_bridge_join(struct dsa_switch *ds, int port,
> >  	a5psw_flooding_set_resolution(a5psw, port, true);
> >  	a5psw_port_mgmtfwd_set(a5psw, port, false);
> >  
> > +	a5psw->bridged_ports |= BIT(port);
> > +
> >  	return 0;
> >  }
> >  
> > @@ -334,6 +332,8 @@ static void a5psw_port_bridge_leave(struct dsa_switch *ds, int port,
> >  {
> >  	struct a5psw *a5psw = ds->priv;
> >  
> > +	a5psw->bridged_ports &= ~BIT(port);
> > +
> >  	a5psw_flooding_set_resolution(a5psw, port, false);
> >  	a5psw_port_mgmtfwd_set(a5psw, port, true);
> >  
> > -- 
> > 2.39.0
> >   
> 
> What about the a5psw_flooding_set_resolution() call for the CPU port, from a5psw_setup()?
> Isn't this an undocumented change? Does this logic in a5psw_port_bridge_leave() still work,
> now that bridged_ports will no longer contain BIT(A5PSW_CPU_PORT)?
> 
> 	/* No more ports bridged */
> 	if (a5psw->bridged_ports == BIT(A5PSW_CPU_PORT))
> 		a5psw->br_dev = NULL;

You are right, this actually disallow to create a bridge multiple
times. I'll fix that.

-- 
Clément Léger,
Embedded Linux and Kernel engineer at Bootlin
https://bootlin.com