Subject: Re: [PATCH net-next] net: pcs: xpcs: Add 2500BASE-X case in get state for XPCS drivers

From: "Russell King (Oracle)" <[email-masked]>
Date: Tue, 26 Sep 2023 12:45:47 +0100

On Tue, Sep 26, 2023 at 02:39:21PM +0300, Serge Semin wrote:
> Hi Raju
> 
> On Mon, Sep 25, 2023 at 01:21:42PM +0530, Raju Lakkaraju wrote:
> > Add DW_2500BASEX case in xpcs_get_state( ) to update speed, duplex and pause
> > Update the port mode and autonegotiation
> > 
> > Signed-off-by: Raju Lakkaraju <[email-masked]>
> > ---
> >  drivers/net/pcs/pcs-xpcs.c | 31 +++++++++++++++++++++++++++++++
> >  drivers/net/pcs/pcs-xpcs.h |  4 ++++
> >  2 files changed, 35 insertions(+)
> > 
> > diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
> > index 4dbc21f604f2..4f89dcedf0fc 100644
> > --- a/drivers/net/pcs/pcs-xpcs.c
> > +++ b/drivers/net/pcs/pcs-xpcs.c
> > @@ -1090,6 +1090,30 @@ static int xpcs_get_state_c37_1000basex(struct dw_xpcs *xpcs,
> >  	return 0;
> >  }
> >  
> > +static int xpcs_get_state_2500basex(struct dw_xpcs *xpcs,
> > +				    struct phylink_link_state *state)
> > +{
> > +	int sts, lpa;
> > +
> > +	sts = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_STS);
> 
> > +	lpa = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_LP_BABL);
> > +	if (sts < 0 || lpa < 0) {
> > +		state->link = false;
> > +		return sts;
> > +	}
> 
> The HW manual says: "The host uses this page to know the link
> partner's ability when the base page is received through Clause 37
> auto-negotiation." Seeing xpcs_config_2500basex() disables
> auto-negotiation and lpa value is unused anyway why do you even need
> to read the LP_BABL register?

Since you have access to the hardware manual, what does it say about
clause 37 auto-negotiation when operating in 2500base-X mode?

Thanks.

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