Re: [PATCH net 1/2] net: stmmac: propagate platform mac_finish errors

[Thomas Karpiniec]

On 16/09/2026 10:03 pm, Mohd Ayaan Anwar wrote:
> On Wed, Sep 16, 2026 at 08:39:49PM +1000, Thomas Karpiniec wrote:
> > From: Thomas Karpiniec <tom@xxxxxxxx>
> >
> > stmmac_mac_finish() discards the platform callback's return value and
> > always reports success to phylink. For example, the Qualcomm ETHQOS
> > callback can return an error from phy_set_mode_ext() if SerDes
> > configuration fails. Phylink then treats the interface as successfully
> > configured and can report carrier even though the SerDes is not ready.
> >
> > Return the platform callback's result so that phylink can report the
> > failure and keep the link down until a subsequent configuration succeeds.
> > Keep returning zero when no platform callback is installed.
> >
> > Fixes: e654cfc718d4 ("net: stmmac: configure SerDes on mac_finish")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Assisted-by: LLM sparse
> > Signed-off-by: Thomas Karpiniec <tom@xxxxxxxx>
> > ---
> >   drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > index 1fb5f804ea23..1350e92943ac 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > @@ -1048,8 +1048,8 @@ static int stmmac_mac_finish(struct phylink_config *config, unsigned int mode,
> >   	struct stmmac_priv *priv = netdev_priv(ndev);
> >   
> >   	if (priv->plat->mac_finish)
> > -		priv->plat->mac_finish(ndev, priv->plat->bsp_priv, mode,
> > -				       interface);
> > +		return priv->plat->mac_finish(ndev, priv->plat->bsp_priv, mode,
> > +					     interface);
> >   
> >   	return 0;
> >   }
>
> Just curious, are you trying to resolve the issue where an interface
> gets created depite:
>    qcom-dwmac-sgmii-phy 8909000.phy: QSERDES_COM_C_READY_STATUS timed-out
>    qcom-ethqos 23040000.ethernet eth0: __stmmac_open: Serdes powerup failed
> in dmesg?
No, I haven't seen that error or any specific SerDes faults. The error 
message you mention appears to be a failure in the serdes_powerup 
callback whereas this is propagating errors from mac_finish.

I just happened to notice the discarded return value while working in 
the area so I don't think it's related.

Tom