netdev - Re: [RFC PATCH] net: dsa: qca8k: Add 802.1q VLAN support

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Date:   Tue, 21 Jul 2020 10:26:07 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Jonathan McDowell <noodles@...th.li>, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Matthew Hagan <mnhagan88@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] net: dsa: qca8k: Add 802.1q VLAN support

On 7/21/20 10:16 AM, Jonathan McDowell wrote:
> This adds full 802.1q VLAN support to the qca8k, allowing the use of
> vlan_filtering and more complicated bridging setups than allowed by
> basic port VLAN support.
> 
> Tested with a number of untagged ports with separate VLANs and then a
> trunk port with all the VLANs tagged on it.

This looks good to me at first glance, at least not seeing obvious
issue, however below are a few questions:

- vid == 0 appears to be unsupported according to your port_vlan_prepare
callback, is this really the case, or is it more a case of VID 0 should
be pvid untagged, which is what dsa_slave_vlan_rx_add_vid() would
attempt to program

- since we have a qca8k_port_bridge_join() callback which programs the
port lookup control register, putting all ports by default in VID==1
does not break per-port isolation between non-bridged and bridged ports,
right?

- since you program the ports with a default VLAN ID upon startup of the
switch driver should not you also set
dsa_switch::configure_vlan_while_not_filtering to indicate to the DSA
layer that there is a VLAN table programmed regardless of VLAN filtering
being enabled in the bridge or not?

See some nitpicks below:

> 
> Signed-off-by: Jonathan McDowell <noodles@...th.li>
> 
> diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> index a5566de82853..cce05493075f 100644
> --- a/drivers/net/dsa/qca8k.c
> +++ b/drivers/net/dsa/qca8k.c
> @@ -408,6 +408,104 @@ qca8k_fdb_flush(struct qca8k_priv *priv)
>  	mutex_unlock(&priv->reg_mutex);
>  }
>  
> +static int
> +qca8k_vlan_access(struct qca8k_priv *priv, enum qca8k_vlan_cmd cmd, u16 vid)
> +{
> +	u32 reg;
> +
> +	/* Set the command and VLAN index */
> +	reg = QCA8K_VTU_FUNC1_BUSY;> +	reg |= cmd;
> +	reg |= vid << QCA8K_VTU_FUNC1_VID_S;
> +
> +	/* Write the function register triggering the table access */
> +	qca8k_write(priv, QCA8K_REG_VTU_FUNC1, reg);
> +
> +	/* wait for completion */
> +	if (qca8k_busy_wait(priv, QCA8K_REG_VTU_FUNC1, QCA8K_VTU_FUNC1_BUSY))
> +		return -1;

Can you propagate the return value from qca8k_busy_wait() directly?

> +
> +	/* Check for table full violation when adding an entry */
> +	if (cmd == QCA8K_VLAN_LOAD) {
> +		reg = qca8k_read(priv, QCA8K_REG_VTU_FUNC1);
> +		if (reg & QCA8K_VTU_FUNC1_FULL)
> +			return -1;
> +	}
> +
> +	return 0;
> +}
> +
> +static int
> +qca8k_vlan_add(struct qca8k_priv *priv, u8 port, u16 vid, bool tagged)
> +{
> +	u32 reg;
> +	int ret;
> +
> +	if (!vid)
> +		return -EOPNOTSUPP;
> +
> +	mutex_lock(&priv->reg_mutex);
> +	ret = qca8k_vlan_access(priv, QCA8K_VLAN_READ, vid);
> +	if (ret >= 0) {

Do an early return upon negative error code instead of reidenting the
code block?

> +		reg = qca8k_read(priv, QCA8K_REG_VTU_FUNC0);
> +		reg |= QCA8K_VTU_FUNC0_VALID | QCA8K_VTU_FUNC0_IVL_EN;
> +		reg &= ~(3 << QCA8K_VTU_FUNC0_EG_MODE_S(port));
> +		if (tagged)
> +			reg |= QCA8K_VTU_FUNC0_EG_MODE_TAG <<
> +					QCA8K_VTU_FUNC0_EG_MODE_S(port);
> +		else
> +			reg |= QCA8K_VTU_FUNC0_EG_MODE_UNTAG <<
> +					QCA8K_VTU_FUNC0_EG_MODE_S(port);
> +
> +		qca8k_write(priv, QCA8K_REG_VTU_FUNC0, reg);
> +		ret = qca8k_vlan_access(priv, QCA8K_VLAN_LOAD, vid);
> +	}
> +	mutex_unlock(&priv->reg_mutex);
> +
> +	return ret;
> +}
> +
> +static int
> +qca8k_vlan_del(struct qca8k_priv *priv, u8 port, u16 vid)
> +{
> +	u32 reg;
> +	u32 mask;
> +	int ret;
> +	int i;
> +	bool del;
> +
> +	mutex_lock(&priv->reg_mutex);
> +	ret = qca8k_vlan_access(priv, QCA8K_VLAN_READ, vid);
> +	if (ret >= 0) {

Likewise
-- 
Florian