Re: [PATCH net-next] net: phy: vitesse: add inband caps and configuration

[Conor Dooley <conor@kernel.org>]

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On Wed, Mar 11, 2026 at 08:28:17AM -0700, Charles Perry wrote:
> On Wed, Mar 11, 2026 at 02:26:11PM +0000, Russell King (Oracle) wrote:
> > On Wed, Mar 11, 2026 at 03:01:35PM +0100, Geert Uytterhoeven wrote:
> > > 	Hi Russell,
> > > 
> > > On Wed, 11 Mar 2026 at 01:07, Russell King <rmk@armlinux.org.uk> wrote:
> > > > Add support for VSC8662 reporting its inband capabilities, and also
> > > > hook to configure the PHY's inband mode.
> > > >
> > > > This fixes a regression in the macb driver caused by commit
> > > > 1338cfef1ff1 ("net: macb: fix SGMII with inband aneg disabled")
> > > 
> > > Fixes: 1338cfef1ff1b958 ("net: macb: fix SGMII with inband aneg disabled")
> > > 
> > > > Reported-by: Conor Dooley <conor@kernel.org>
> > > > Link: https://lore.kernel.org/r/20260304-nebulizer-rounding-40fbc81a2ba1@spud
> > > 
> > > s/Link/Closes/
> > 
> > I avoided it because any other PHY used with macb that is also connected
> > via SGMII will run into this same issue. It just happens that adding
> > this support fixes the above commit.
> > 
> > Conversely, we have stmmac, which unconditionally enables SGMII inband
> > at the MAC end no matter what phylink says to do, and should this
> > PHY be used with this patch in a stmmac system, it will cause that to
> > break, because we end up with either end misconfigured.
> > 
> 
> macb also unconditionally activated inband aneg before I added the
> ->pcs_config() callback.
> 
> One of the way I think we could fix macb is by adding:
> 
>         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;
> +               bp->phylink_config.default_an_inband = true;
>         }
> 
> in macb_mii_probe(). This would force phylink into using inband aneg
> every time, unless there's a fixed link or the PHY explicitly doesn't
> support in-band. This would make it compatible with legacy system that were
> setup with in-band aneg activated. It would fix MPFS without the need for
> this patch or device-tree modifications ('managed = "in-band-status"').

No commentary on whether or not this is the correct approach, but it
restores functionality on both boards I have on-hand.

Thanks,
Conor.

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