Re: [PATCH net-next v2 13/14] net: stmmac: tc956x: add TC956x/QPS615 support

[Alex Elder]

On 6/5/26 11:05 AM, Maxime Chevallier wrote:
> Hi Alex,
>
> On 6/5/26 03:00, Alex Elder wrote:
> > From: Daniel Thompson <daniel@xxxxxxxxxxxx>
> >
> > Toshiba TC956x is an Ethernet AVB/TSN bridge and is essentially a
> > small and highly-specialized SoC. TC956x includes an "eMAC" subsystem
> > that can be accessed, along with several other peripherals, via two
> > PCIe endpoint functions. There is a main driver for the endpoint that
> > decomposes things and creates auxiliary bus devices to model the SoC.
> >
> > The eMAC consists of a Designware XGMAC, XPCS and PMA. Each eMAC is
> > supported by an MSIGEN that bridges TC956x level interrupts to PCIe
> > MSIs.
> >
> > Add a driver for the eMAC/MSIGEN combination.
> >
> > Co-developed-by: Alex Elder <elder@xxxxxxxxxxxx>
> > Signed-off-by: Alex Elder <elder@xxxxxxxxxxxx>
> > Signed-off-by: Daniel Thompson <daniel@xxxxxxxxxxxx>
> > ---
> [...]
>
> > +static int tc956x_lookup_max_speed(phy_interface_t phy_interface)
> > +{
> > +	switch (phy_interface) {
> > +	case PHY_INTERFACE_MODE_SGMII:
>
> The SGMII definition we use in the kernel is the Cisco SGMII de-facto
> standard that only supports 10/100/1000M. Some vendors use flavours with
> names such as HS-SGMII and such, that's basically SGMII clocked at 2.5G
> with aneg disabled. It kinda becomes 2500BaseX then.

So for SGMII then, the max speed returned/used should be
SPEED_1000, correct?  And for 2500BASEX it's SPEED_2500.
(I'll fix this.)

For USXGMII I presume we'd use SPEED_10000 as the max_speed.

Can someone explain when the plat_stmmacenet_data->max_speed value
must be set?  It seems like plat_stmmacenet_data->phy_interface
should normally imply the right maximum speed.  It looks like
phylink_interface_max_speed() has a big switch statement related
to this.

Thanks.

					-Alex

> So all in all, we don't support 2500M on SGMII.
>
> > +	case PHY_INTERFACE_MODE_2500BASEX:
> > +		return SPEED_2500;
> > +
> > +	default:
> > +		return -EOPNOTSUPP;
> > +	}
>
> Maxime