Re: [net-next PATCH 2/3] net: dsa: qca8k: make learning configurable and keep off if standalone

[Vladimir Oltean <olteanv@gmail.com>]

On Mon, Jul 24, 2023 at 05:30:57AM +0200, Christian Marangi wrote:
> Address learning should initially be turned off by the driver for port
> operation in standalone mode, then the DSA core handles changes to it
> via ds->ops->port_bridge_flags().
> 
> Currently this is not the case for qca8k where learning is enabled
> unconditionally in qca8k_setup for every user port.
> 
> Handle ports configured in standalone mode by making the learning
> configurable and not enabling it by default.
> 
> Implement .port_pre_bridge_flags and .port_bridge_flags dsa ops to
> enable learning for bridge that request it and tweak
> .port_stp_state_set to correctly disable learning when port is
> configured in standalone mode.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> ---

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>

Small nitpick below.

>  drivers/net/dsa/qca/qca8k-8xxx.c   |  7 +++--
>  drivers/net/dsa/qca/qca8k-common.c | 44 ++++++++++++++++++++++++++++++
>  drivers/net/dsa/qca/qca8k.h        |  6 ++++
>  3 files changed, 54 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/dsa/qca/qca8k-8xxx.c b/drivers/net/dsa/qca/qca8k-8xxx.c
> index ae088a4df794..31552853fdd4 100644
> --- a/drivers/net/dsa/qca/qca8k-8xxx.c
> +++ b/drivers/net/dsa/qca/qca8k-8xxx.c
> @@ -1870,9 +1870,8 @@ qca8k_setup(struct dsa_switch *ds)
>  			if (ret)
>  				return ret;
>  
> -			/* Enable ARP Auto-learning by default */
> -			ret = regmap_set_bits(priv->regmap, QCA8K_PORT_LOOKUP_CTRL(i),
> -					      QCA8K_PORT_LOOKUP_LEARN);
> +			ret = regmap_clear_bits(priv->regmap, QCA8K_PORT_LOOKUP_CTRL(i),
> +						QCA8K_PORT_LOOKUP_LEARN);
>  			if (ret)
>  				return ret;
>  
> @@ -1978,6 +1977,8 @@ static const struct dsa_switch_ops qca8k_switch_ops = {
>  	.port_change_mtu	= qca8k_port_change_mtu,
>  	.port_max_mtu		= qca8k_port_max_mtu,
>  	.port_stp_state_set	= qca8k_port_stp_state_set,
> +	.port_pre_bridge_flags	= qca8k_port_pre_bridge_flags,
> +	.port_bridge_flags	= qca8k_port_bridge_flags,
>  	.port_bridge_join	= qca8k_port_bridge_join,
>  	.port_bridge_leave	= qca8k_port_bridge_leave,
>  	.port_fast_age		= qca8k_port_fast_age,
> diff --git a/drivers/net/dsa/qca/qca8k-common.c b/drivers/net/dsa/qca/qca8k-common.c
> index 13b8452ce5b2..e53694d2852a 100644
> --- a/drivers/net/dsa/qca/qca8k-common.c
> +++ b/drivers/net/dsa/qca/qca8k-common.c
> @@ -565,9 +565,26 @@ int qca8k_get_mac_eee(struct dsa_switch *ds, int port,
>  	return 0;
>  }
>  
> +static int qca8k_port_configure_learning(struct dsa_switch *ds, int port,
> +					 bool learning)
> +{
> +	struct qca8k_priv *priv = ds->priv;
> +
> +	if (learning)
> +		return regmap_set_bits(priv->regmap,
> +				       QCA8K_PORT_LOOKUP_CTRL(port),
> +				       QCA8K_PORT_LOOKUP_LEARN);
> +	else
> +		return regmap_clear_bits(priv->regmap,
> +					 QCA8K_PORT_LOOKUP_CTRL(port),
> +					 QCA8K_PORT_LOOKUP_LEARN);
> +}
> +
>  void qca8k_port_stp_state_set(struct dsa_switch *ds, int port, u8 state)
>  {
> +	struct dsa_port *dp = dsa_to_port(ds, port);
>  	struct qca8k_priv *priv = ds->priv;
> +	bool learning = false;
>  	u32 stp_state;
>  
>  	switch (state) {
> @@ -582,8 +599,11 @@ void qca8k_port_stp_state_set(struct dsa_switch *ds, int port, u8 state)
>  		break;
>  	case BR_STATE_LEARNING:
>  		stp_state = QCA8K_PORT_LOOKUP_STATE_LEARNING;
> +		learning = dp->learning;
>  		break;
>  	case BR_STATE_FORWARDING:
> +		learning = dp->learning;
> +		fallthrough;
>  	default:
>  		stp_state = QCA8K_PORT_LOOKUP_STATE_FORWARD;
>  		break;
> @@ -591,6 +611,30 @@ void qca8k_port_stp_state_set(struct dsa_switch *ds, int port, u8 state)
>  
>  	qca8k_rmw(priv, QCA8K_PORT_LOOKUP_CTRL(port),
>  		  QCA8K_PORT_LOOKUP_STATE_MASK, stp_state);
> +
> +	qca8k_port_configure_learning(ds, port, learning);
> +}
> +
> +int qca8k_port_pre_bridge_flags(struct dsa_switch *ds, int port,
> +				struct switchdev_brport_flags flags,
> +				struct netlink_ext_ack *extack)
> +{
> +	if (flags.mask & ~BR_LEARNING)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +int qca8k_port_bridge_flags(struct dsa_switch *ds, int port,
> +			    struct switchdev_brport_flags flags,
> +			    struct netlink_ext_ack *extack)
> +{
> +	int ret;
> +
> +	ret = qca8k_port_configure_learning(ds, port,
> +					    flags.val & BR_LEARNING);
> +
> +	return ret;

I worry that the way in this is formulated will attract patches from
kernel janitors to simplify it to:

	return qca8k_port_configure_learning(...)

I agree that it's not strictly necessary to check flags.mask when
port_pre_bridge_flags supports a single flag, but if you did that and
structured the code for more future flags, you could avoid that.

	int ret;

	if (flags.mask & BR_LEARNING) {
		ret = qca8k_port_configure_learning(...,
						    flags.val & BR_LEARNING);
		if (ret)
			return ret;
	}

	return 0;

Anyway, probably not a big deal.

>  }
>  
>  int qca8k_port_bridge_join(struct dsa_switch *ds, int port,
> diff --git a/drivers/net/dsa/qca/qca8k.h b/drivers/net/dsa/qca/qca8k.h
> index c5cc8a172d65..8f88b7db384d 100644
> --- a/drivers/net/dsa/qca/qca8k.h
> +++ b/drivers/net/dsa/qca/qca8k.h
> @@ -522,6 +522,12 @@ int qca8k_get_mac_eee(struct dsa_switch *ds, int port, struct ethtool_eee *e);
>  
>  /* Common bridge function */
>  void qca8k_port_stp_state_set(struct dsa_switch *ds, int port, u8 state);
> +int qca8k_port_pre_bridge_flags(struct dsa_switch *ds, int port,
> +				struct switchdev_brport_flags flags,
> +				struct netlink_ext_ack *extack);
> +int qca8k_port_bridge_flags(struct dsa_switch *ds, int port,
> +			    struct switchdev_brport_flags flags,
> +			    struct netlink_ext_ack *extack);
>  int qca8k_port_bridge_join(struct dsa_switch *ds, int port,
>  			   struct dsa_bridge bridge,
>  			   bool *tx_fwd_offload,
> -- 
> 2.40.1
>