Re: [PATCH net-next v3 1/2] net: macb: Poll for link state changes when using the internal PCS.

["Théo Lebrun" <theo.lebrun@bootlin.com>]

Hello Nathan,

On Wed Jul 29, 2026 at 9:21 PM CEST, Nathan Whitehorn wrote:
> When used with an offboard transceiver (e.g. an SFP), link state needs
> to be measured at the PCS rather than an onboard PHY. Poll the link
> state when the PCS is active to allow the kernel to detect link state
> changes in this case.
>
> Signed-off-by: Nathan Whitehorn <nwhitehorn@pa.msu.edu>
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index d394f1f43b68..c15a9c7e69d3 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -1025,6 +1025,7 @@ static int macb_mii_probe(struct net_device *dev)
>  	struct macb *bp = netdev_priv(dev);
>  
>  	bp->phylink_sgmii_pcs.ops = &macb_phylink_pcs_ops;
> +	bp->phylink_sgmii_pcs.poll = true;
>  	bp->phylink_usx_pcs.ops = &macb_phylink_usx_pcs_ops;
>  
>  	bp->phylink_config.dev = &dev->dev;

Hardware has an IRQ for that, would you want to use it instead of
polling? The user guide contains more info.

   /* Bitfields in ISR/IER/IDR/IMR */
   ...
   #define MACB_ISR_LINK_OFFSET  9 /* Enable link change interrupt */
   #define MACB_ISR_LINK_SIZE 1
   ...

I've checked with an on-board SGMII PHY and I get an IRQ once unmasked.

If you don't care, then:

Reviewed-by: Théo Lebrun <theo.lebrun@bootlin.com>

Regards,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com