Re: [PATCH net-next v6 5/5] net: dsa: yt921x: Add DCB/QoS support

[Vladimir Oltean]

On Sat, Jan 31, 2026 at 10:18:51AM +0800, David Yang wrote:
> @@ -1774,8 +1778,11 @@ yt921x_vlan_aware_set(struct yt921x_priv *priv, int port, bool vlan_aware)
>  {
>  	u32 ctrl;
>  
> +	/* Abuse SVLAN for PCP parsing without polluting the FDB - it just works
> +	 * despite YT921X_VLAN_CTRL_SVLAN_EN never being set
> +	 */

Why "abuse" - what else does this setting affect? Does the port not
remain VLAN-unaware w.r.t. filtering/forwarding destinations?

How is the unused YT921X_VLAN_CTRL_PRIO_EN field from VLAN table entries
related to VLAN PCP parsing?

>  	if (!vlan_aware)
> -		ctrl = 0;
> +		ctrl = YT921X_PORT_IGR_TPIDn_STAG(0);
>  	else
>  		ctrl = YT921X_PORT_IGR_TPIDn_CTAG(0);
>  	return yt921x_reg_write(priv, YT921X_PORTn_IGR_TPID(port), ctrl);