Re: [PATCH net-next v10 4/9] net: dsa: lan9645x: add basic dsa driver for LAN9645X

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Missing FDB operations and omission of the CPU port in PGID_UC breaks unicast IP traffic to the CPU.
--

--- Patch [4]: [PATCH net-next v10 4/9] net: dsa: lan9645x: add basic dsa driver for LAN9645X ---
commit 996cf37c0fe28c352442c3b82c0b401974b8f66a
Author: Jens Emil Schulz Østergaard <jensemil.schulzostergaard@microchip.com>

net: dsa: lan9645x: add basic dsa driver for LAN9645X
    
Add the LAN9645X basic DSA driver with initialization, parent regmap requests,
port module initialization for NPI, CPU ports and front ports, and phylink
integration for MAC side configuration.

> diff --git a/drivers/net/dsa/microchip/lan9645x/lan9645x_main.c b/drivers/net/dsa/microchip/lan9645x/lan9645x_main.c
> new file mode 100644
> index 0000000000000..b253813518c20
> --- /dev/null
> +++ b/drivers/net/dsa/microchip/lan9645x/lan9645x_main.c

[ ... ]

> @@ -0,0 +1,447 @@

[ ... ]

> +static int lan9645x_setup(struct dsa_switch *ds)
> +{

[ ... ]

> +	/* Multicast to all front ports */
> +	lan_wr(front_ports, lan9645x, ANA_PGID(PGID_MC));
> +
> +	/* IP multicast to all front ports */
> +	lan_wr(front_ports, lan9645x, ANA_PGID(PGID_MCIPV4));
> +	lan_wr(front_ports, lan9645x, ANA_PGID(PGID_MCIPV6));
> +
> +	/* Unicast to all front ports */
> +	lan_wr(front_ports, lan9645x, ANA_PGID(PGID_UC));

[Severity: High]
Does omitting the CPU port module (BIT(lan9645x->num_phys_ports)) from the
unknown unicast flooding mask (PGID_UC) prevent unicast traffic from reaching
the CPU?

Since hardware learning is disabled in lan9645x_port_setup() via
ANA_PORT_CFG_LEARN_ENA_SET(0), and the lan9645x_switch_ops struct lacks a
port_fdb_add callback to statically program the CPU's MAC address, unicast
frames destined for the CPU will be treated as unknown unicast.

Because PGID_UC only includes front_ports, it appears these unknown unicast
frames will be flooded to the front ports but not to the CPU, effectively
breaking unicast IP connectivity (such as ARP replies) to the host.

> +
> +	/* Broadcast to cpu and all front ports */
> +	lan_wr(BIT(lan9645x->num_phys_ports) | front_ports, lan9645x,
> +	       ANA_PGID(PGID_BC));

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260713-dsa_lan9645x_switch_driver_base-v10-0-a4886a08fb15@microchip.com?part=4