Re: [PATCH net-next V2 5/5] net: lan743x: Add Support for 2.5G SFP with 2500Base-X Interface

[Raju Lakkaraju]

The 09/11/2024 22:01, Maxime Chevallier wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Wed, 11 Sep 2024 19:31:01 +0200
> Andrew Lunn <andrew@xxxxxxx> wrote:
> 
> > > @@ -3359,6 +3362,7 @@ static int lan743x_phylink_create(struct lan743x_adapter *adapter)
> > >     lan743x_phy_interface_select(adapter);
> > >
> > >     switch (adapter->phy_interface) {
> > > +   case PHY_INTERFACE_MODE_2500BASEX:
> > >     case PHY_INTERFACE_MODE_SGMII:
> > >             __set_bit(PHY_INTERFACE_MODE_SGMII,
> > >                       adapter->phylink_config.supported_interfaces);
> >
> > I _think_ you also need to set the PHY_INTERFACE_MODE_2500BASEX bit in
> > phylink_config.supported_interfaces if you actually support it.
> 
> It's actually being set a bit below. However that raises the
> question of why.
> 
> On the variant that don't have this newly-introduced SFP support but do
> have sgmii support (!is_sfp_support_en && is_sgmii_en), can this chip
> actually support 2500BaseX ?

Yes. 
PCI11010/PCI11414 chip's PCS support SGMII/2500Baxe-X I/F at 2.5Gpbs
We need to over clocking at a bit rate of 3.125 Gbps for 2.5Gbps event SGMII
I/F

>From data sheet:
"The SGMII interface also supports over clocking at a bit rate of 3.125 Gbps for an effective 2.5 Gbps data rate. 10 and
100 Mbps modes are also scaled up by 2.5x but are most likely not useful."

> 
> If so, is there a point in getting a different default interface
> returned from lan743x_phy_interface_select() depending on wether or not
> there's SFP support ?

Yes.

This LAN743x driver support following chips
 1. LAN7430 - GMII I/F
 2. LAN7431 - MII I/F
 3. PCI11010/PCI11414 - RGMII or SGMII/1000Base-X/2500Base-X

> 
> Maxime
> 

-- 
Thanks,                                                                         
Raju