Re: [PATCH net 1/3] net: hns3: fix loopback test of serdes and phy is failed if duplex is half

[Jijie Shao]

on 2025/9/18 0:58, Andrew Lunn wrote:
> On Wed, Sep 17, 2025 at 08:29:52PM +0800, Jijie Shao wrote:
> > If duplex setting is half, mac and phy can not transmit and receive data
> > at the same time.
> Lets think about the fundamentals of Ethernet, MII and half duplex.
>
> Is this specific to your MAC/PHY combination, or just generally true?
>
> Should this is solved in phylib, because it is true for every MAC/PHY
> combination? phylib returning -EINAL to phy_loopback() would seem like
> the correct thing to do.
>
> Is it specific to your PHY, but independent of the MAC?  Then the PHY
> should return -EINVAL in its set_loopback() method.

My idea is to prevent customers from seeing command failures,
so I switched from half-duplex to full-duplex for testing.
But it doesn't seem quite appropriate.


> > +	hdev->hw.mac.duplex_last = phydev->duplex;
> > +
> > +	ret = phy_set_bits(phydev, MII_BMCR, BMCR_FULLDPLX);
> A MAC driver should not be doing this. What if the PHY is C45 only?
> And Marvell PHYs need a soft reset before such an operation take
> effect.
>
>      Andrew

Thanks for the reminder.

Thanks，
Jijie Shao