Re: [RFC PATCH net-next 2/2] net: dsa: felix: offload port priority

[Andrew Lunn <andrew@lunn.ch>]

On Wed, Jan 13, 2021 at 05:41:39PM +0200, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.oltean@nxp.com>
> 
> Even though we should really share the implementation with the ocelot
> switchdev driver, that one needs a little bit of rework first, since its
> struct ocelot_port_tc only supports one tc matchall action at a time,
> which at the moment is used for port policers. Whereas DSA keeps a list
> of port-based actions in struct dsa_slave_priv::mall_tc_list, so it is
> much more easily extensible. It is too tempting to add the implementation
> for the port priority directly in Felix at the moment, which is what we
> do.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
>  drivers/net/dsa/ocelot/felix.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
> index 768a74dc462a..5cc42c3aaf0d 100644
> --- a/drivers/net/dsa/ocelot/felix.c
> +++ b/drivers/net/dsa/ocelot/felix.c
> @@ -739,6 +739,20 @@ static void felix_port_policer_del(struct dsa_switch *ds, int port)
>  	ocelot_port_policer_del(ocelot, port);
>  }
>  
> +static int felix_port_priority_set(struct dsa_switch *ds, int port,
> +				   struct dsa_mall_skbedit_tc_entry *skbedit)
> +{
> +	struct ocelot *ocelot = ds->priv;
> +
> +	ocelot_rmw_gix(ocelot,
> +		       ANA_PORT_QOS_CFG_QOS_DEFAULT_VAL(skbedit->priority),

No range check? Seems like -ERANGE or similar would help avoid
surprises when somebody asks for an unsupported priority and it gets
masked to something much lower.

       Andrew