Re: [PATCH net-next] net: macb: set default_an_inband to true for SGMII

[Conor Dooley]

On Thu, Mar 12, 2026 at 06:38:55AM -0700, Charles Perry wrote:
> Most platforms using GEM in SGMII mode use in-band autonegotiation
> because it is on by default in GEM's 1G PCS and is always on since
> commit e276e5e40e92 ("net: macb: Disable PCS auto-negotiation for SGMII
> fixed-link mode"). Leave it on if possible using the "default_an_inband"
> flag of "struct phylink_config" so that platforms that lack in-band
> autonegotiation configurability at the PHY do not break with commit
> 1338cfef1ff1 ("net: macb: fix SGMII with inband aneg disabled") which
> will turn off in-band autoneg for non hot pluggable PHYs.
> 
> Once the majority of the PHY drivers that support SGMII have the
> ->config_inband() callback, this commit could be reverted so that non
> hot pluggable PHY use outband negotiation with macb, like its the case
> for other MACs.
> 
> Fixes: 1338cfef1ff1 ("net: macb: fix SGMII with inband aneg disabled")
> Closes: https://lore.kernel.org/r/20260304-nebulizer-rounding-40fbc81a2ba1@spud

Reported-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>

> Tested-by: Conor Dooley <conor@xxxxxxxxxx>

Just as an FYI, you shouldn't insert tags that "certify" the quality of
your patch that you weren't explicitly given. Reported-by/Suggested-by
you can conjure up yourself where appropriate, but Tested-by/Acked-by/Reviewed-by
need more care.

But of course, I did test it, and it restored functionality on both
boards that I have here, so:
Tested-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>

Cheers,
Conor.

> Signed-off-by: Charles Perry <charles.perry@xxxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 963a5d4e1a88..d1fc6a9b9fe5 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -838,6 +838,12 @@ static int macb_mii_probe(struct net_device *dev)
>  	if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII) {
>  		bp->phylink_config.poll_fixed_state = true;
>  		bp->phylink_config.get_fixed_state = macb_get_pcs_fixed_state;
> +		/* The PCSAUTONEG bit in PCSCNTRL is on out of reset. Setting
> +		 * default_an_inband to true tells phylink to turn it off only
> +		 * if necessary (e.g. a fixed link or a PHY that doesn't support
> +		 * inband).
> +		 */
> +		bp->phylink_config.default_an_inband = true;
>  	}
>  
>  	bp->phylink_config.mac_capabilities = MAC_ASYM_PAUSE |
> -- 
> 2.47.3
>

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