Re: [PATCH net-next 2/3] net: pcs: pcs-mtk-lynxi: implement pcs_inband_caps() method

[Daniel Golle <daniel@makrotopia.org>]

On Thu, Jan 02, 2025 at 08:59:13AM +0000, Russell King (Oracle) wrote:
> On Tue, Dec 17, 2024 at 08:49:58AM +0100, Eric Woudstra wrote:
> > On 12/5/24 10:42 AM, Russell King (Oracle) wrote:
> > > Report the PCS in-band capabilities to phylink for the LynxI PCS.
> > > 
> > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > Reviewed-by: Daniel Golle <daniel@makrotopia.org>
> > > ---
> > >  drivers/net/pcs/pcs-mtk-lynxi.c | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > > 
> > > diff --git a/drivers/net/pcs/pcs-mtk-lynxi.c b/drivers/net/pcs/pcs-mtk-lynxi.c
> > > index 4f63abe638c4..7de804535229 100644
> > > --- a/drivers/net/pcs/pcs-mtk-lynxi.c
> > > +++ b/drivers/net/pcs/pcs-mtk-lynxi.c
> > > @@ -88,6 +88,21 @@ static struct mtk_pcs_lynxi *pcs_to_mtk_pcs_lynxi(struct phylink_pcs *pcs)
> > >  	return container_of(pcs, struct mtk_pcs_lynxi, pcs);
> > >  }
> > >  
> > > +static unsigned int mtk_pcs_lynxi_inband_caps(struct phylink_pcs *pcs,
> > > +					      phy_interface_t interface)
> > > +{
> > > +	switch (interface) {
> > > +	case PHY_INTERFACE_MODE_1000BASEX:
> > > +	case PHY_INTERFACE_MODE_2500BASEX:
> > 
> > Isn't this the place now where to report to phylink, that this PCS does
> > not support in-band at 2500base-x?
> 
> No - look at the arguments to this function. What arguments would this
> function make a decision whether in-band is supported in any interface
> mode?
> 
> The correct place is the .pcs_inband_caps(), which from reading the
> code, I understood that in-band can be used at 2500base-X with this
> PCS. See
> https://patch.msgid.link/E1tJ8NR-006L5P-E3@rmk-PC.armlinux.org.uk
> which was merged at the beginning of December, and if you are correct,
> the patch was wrong.

Yes, that patch was wrong. Neither is QSGMII supported at all by the
LynxI hardware, nor can in-band-status be used in 2500Base-X mode.
I will send a patch to fix that.