linux-kernel - Re: [PATCH net-next] net: dsa: mt7530: add support for changing DSA master

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Message-ID: <20230210185629.gfbaibewnc5u3tgs@skbuf>
Date:   Fri, 10 Feb 2023 20:56:29 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     arinc9.unal@...il.com
Cc:     Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>, 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>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Richard van Schagen <richard@...terhints.com>,
        Arınç ÜNAL <arinc.unal@...nc9.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, erkin.bozoglu@...ont.com
Subject: Re: [PATCH net-next] net: dsa: mt7530: add support for changing DSA
 master

On Fri, Feb 10, 2023 at 08:29:43PM +0300, arinc9.unal@...il.com wrote:
> From: Richard van Schagen <richard@...terhints.com>
> 
> Add support for changing the master of a port on the MT7530 DSA subdriver.
> 
> [ arinc.unal@...nc9.com: Wrote subject and changelog ]
> 
> Tested-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> Signed-off-by: Richard van Schagen <richard@...terhints.com>
> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> ---
>  drivers/net/dsa/mt7530.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index b5ad4b4fc00c..04bb4986454e 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -1072,6 +1072,38 @@ mt7530_port_disable(struct dsa_switch *ds, int port)
>  	mutex_unlock(&priv->reg_mutex);
>  }
>  
> +static int
> +mt7530_port_change_master(struct dsa_switch *ds, int port,
> +				       struct net_device *master,
> +				       struct netlink_ext_ack *extack)

alignment

> +{
> +	struct mt7530_priv *priv = ds->priv;
> +	struct dsa_port *dp = dsa_to_port(ds, port);
> +	struct dsa_port *cpu_dp = master->dsa_ptr;
> +	int old_cpu = dp->cpu_dp->index;
> +	int new_cpu = cpu_dp->index;

I believe you need to reject LAG DSA masters.

> +
> +	mutex_lock(&priv->reg_mutex);
> +
> +	/* Move old to new cpu on User port */
> +	priv->ports[port].pm &= ~PCR_MATRIX(BIT(old_cpu));
> +	priv->ports[port].pm |= PCR_MATRIX(BIT(new_cpu));
> +
> +	mt7530_rmw(priv, MT7530_PCR_P(port), PCR_MATRIX_MASK,
> +		   priv->ports[port].pm);
> +
> +	/* Move user port from old cpu to new cpu */
> +	priv->ports[old_cpu].pm &= ~PCR_MATRIX(BIT(port));
> +	priv->ports[new_cpu].pm |= PCR_MATRIX(BIT(port));
> +
> +	mt7530_write(priv, MT7530_PCR_P(old_cpu), priv->ports[old_cpu].pm);
> +	mt7530_write(priv, MT7530_PCR_P(new_cpu), priv->ports[new_cpu].pm);

- who writes to the "pm" field of CPU ports?
- how does this line up with your other patch which said (AFAIU) that
  the port matrix of CPU ports should be 0 and that should be fine?
- read/modify/write (rmw) using PCR_MATRIX_MASK rather than mt7530_write().
  That overwrites the other PCR fields.

> +
> +	mutex_unlock(&priv->reg_mutex);
> +
> +	return 0;
> +}
> +
>  static int
>  mt7530_port_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
>  {
> @@ -3157,6 +3189,7 @@ static const struct dsa_switch_ops mt7530_switch_ops = {
>  	.set_ageing_time	= mt7530_set_ageing_time,
>  	.port_enable		= mt7530_port_enable,
>  	.port_disable		= mt7530_port_disable,
> +	.port_change_master	= mt7530_port_change_master,
>  	.port_change_mtu	= mt7530_port_change_mtu,
>  	.port_max_mtu		= mt7530_port_max_mtu,
>  	.port_stp_state_set	= mt7530_stp_state_set,
> -- 
> 2.37.2
>