Re: [PATCH v5 net-next 08/10] net: dsa: felix: convert to the new .{set,del}_tag_protocol DSA API

On 1/20/2021 6:36 PM, Vladimir Oltean wrote:

From: Vladimir Oltean <vladimir.oltean@nxp.com>

In expectation of the new tag_ocelot_8021q tagger implementation, we
need to be able to do runtime switchover between one tagger and another.
So we must implement the .set_tag_protocol() and .del_tag_protocol() for
the current NPI-based tagger.

We move the felix_npi_port_init function in expectation of the future
driver configuration necessary for tag_ocelot_8021q: we would like to
not have the NPI-related bits interspersed with the tag_8021q bits.

Note that the NPI port is no longer configured when the .setup() method
concludes - aka when ocelot_init() and ocelot_init_port() are called.
So we need to set the replicator groups - the PGIDs - again, when the
NPI port is configured - in .set_tag_protocol(). So we export and call
ocelot_apply_bridge_fwd_mask().

The conversion from this:

	ocelot_write_rix(ocelot,
			 ANA_PGID_PGID_PGID(GENMASK(ocelot->num_phys_ports, 0)),
			 ANA_PGID_PGID, PGID_UC);

to this:

	cpu_flood = ANA_PGID_PGID_PGID(BIT(ocelot->num_phys_ports));
	ocelot_rmw_rix(ocelot, cpu_flood, cpu_flood, ANA_PGID_PGID, PGID_UC);

is perhaps non-trivial, but is nonetheless non-functional. The PGID_UC
(replicator for unknown unicast) is already configured out of hardware
reset to flood to all ports except ocelot->num_phys_ports (the CPU port
module). All we change is that we use a read-modify-write to only add
the CPU port module to the unknown unicast replicator, as opposed to
doing a full write to the register.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian