Re: [PATCH net-next 14/15] net: mscc: ocelot: split assignment of the cpu port into a separate function

[Andrew Lunn <andrew@lunn.ch>]

> +void ocelot_set_cpu_port(struct ocelot *ocelot, int cpu,
> +			 enum ocelot_tag_prefix injection,
> +			 enum ocelot_tag_prefix extraction)
> +{
> +	/* Configure and enable the CPU port. */
> +	ocelot_write_rix(ocelot, 0, ANA_PGID_PGID, cpu);
> +	ocelot_write_rix(ocelot, BIT(cpu), ANA_PGID_PGID, PGID_CPU);
> +	ocelot_write_gix(ocelot, ANA_PORT_PORT_CFG_RECV_ENA |
> +			 ANA_PORT_PORT_CFG_PORTID_VAL(cpu),
> +			 ANA_PORT_PORT_CFG, cpu);
> +
> +	/* If the CPU port is a physical port, set up the port in Node
> +	 * Processor Interface (NPI) mode. This is the mode through which
> +	 * frames can be injected from and extracted to an external CPU.
> +	 * Only one port can be an NPI at the same time.
> +	 */
> +	if (cpu < ocelot->num_phys_ports) {
> +		ocelot_write(ocelot, QSYS_EXT_CPU_CFG_EXT_CPUQ_MSK_M |
> +			     QSYS_EXT_CPU_CFG_EXT_CPU_PORT(cpu),
> +			     QSYS_EXT_CPU_CFG);
> +	}

If a port is not a physical port, what is it? Is it actually an error
if the CPU port is not physical? Should we be returning -EINVAL here,
indicating the device tree is bad?

	   Andrew