Re: [PATCH net-next v3 6/9] net: dsa: realtek: rtl8365mb: use raw VID for PVID on family D

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- [Medium] This patch adds a family D branch to
  rtl8365mb_vlan_port_get_pvid()…

--

net: dsa: realtek: rtl8365mb: use raw VID for PVID on family D

On family D chips, this commit reads the PVID as a raw 12-bit VID from the
per-port register at 0x0700 + port. Family C keeps using the VLAN MC table
index. It also adds direct-VID variants of the PVID set and clear paths
that skip the MC table on family D.

> diff --git a/drivers/net/dsa/realtek/rtl8365mb_vlan.c b/drivers/net/dsa/realtek/rtl8365mb_vlan.c
> index 2c4c5baf93f10..ccfa764b98125 100644
> --- a/drivers/net/dsa/realtek/rtl8365mb_vlan.c
> +++ b/drivers/net/dsa/realtek/rtl8365mb_vlan.c

[ ... ]

> @@ -742,11 +751,25 @@ int rtl8365mb_vlan_port_get_pvid(struct realtek_priv *priv, int port, u16 *pvid)
>  	u8 vlanmc_idx;
>  	int ret;
>  
> -	ret = rtl8365mb_vlan_get_pvid_mc(priv, port, &vlanmc_idx, &vlanmc);
> -	if (ret)
> -		return ret;
> +	if (rtl8365mb_get_family(priv) == RTL8365MB_FAMILY_D) {
> +		u32 data;
> +
> +		ret = regmap_read(priv->map,
> +				  RTL8365MB_D_VLAN_PVID_CTRL_REG(port),
> +				  &data);
> +		if (ret)
> +			return ret;
> +
> +		*pvid = data & RTL8365MB_D_VLAN_PVID_CTRL_MASK;

[Severity: Medium]
Can this report a PVID that the bridge never configured?

The kernel-doc for rtl8365mb_vlan_port_get_pvid() still says:

 * Returns the port PVID if defined or 0 if not.

On family C that holds. An unconfigured port has VLANMC index 0, and
rtl8365mb_vlan_get_pvid_mc() memsets the entry, so evid is 0. On family D
this branch returns whatever the register holds.

rtl8365mb_vlan_setup() only calls
rtl8365mb_port_vlan_filtering(ds, dp->index, false, NULL) for each port
and then sets RTL8365MB_VLAN_CTRL_EN_MASK. Nothing there writes 0 to the
family D PVID registers. The only code that writes 0 is
rtl8365mb_vlan_pvid_port_clear_direct(), and it only does so when the
bridge clears a VID that matches the register.

After rtl8365mb_reset_chip(), the register holds its hardware default or
a value loaded from EEPROM. If that value is non-zero, two callers act on
it.

In rtl8365mb_port_vlan_filtering() with vlan_filtering set:

	if (pvid_vid)
		accepted_frame = RTL8365MB_FRAME_TYPE_ANY_FRAME;

Here, a VLAN-filtering port with no bridge PVID (for example a bridge
with default_pvid 0) would accept untagged frames into the stale VID.

In the undo_set_pvid path of rtl8365mb_port_vlan_add():

	if (pvid_vid)
		(void)rtl8365mb_vlan_pvid_port_set(ds, port, pvid_vid,
						   NULL);

On error, this path would program the stale VID as the PVID.

I couldn't confirm the reset value of these registers from the tree, so
this depends on the hardware or EEPROM default. The family D get_pvid
branch and rtl8365mb_vlan_setup() also look unchanged at the end of the
series.

Should rtl8365mb_vlan_setup() clear the family D PVID registers to 0? That
would match the family C convention of VLANMC index 0 as the neutral
PVID.

> +	} else {
> +		ret = rtl8365mb_vlan_get_pvid_mc(priv, port, &vlanmc_idx,
> +						 &vlanmc);
> +		if (ret)
> +			return ret;
> +
> +		*pvid = vlanmc.evid;
> +	}

[ ... ]

-- 
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