Re: [RFC net-next v2] net:dsa:yt922x: Add support for Motorcomm YT922x

[Kyle Switch]

On 8/28/26 21:19, Andrew Lunn wrote:
> > > > +static int yt922x_port_sds_init(struct yt921x_priv *priv, int port,
> > > > +				phy_interface_t interface)
> > > > +{
> > > > +	int addr;
> > > > +	u16 data;
> > > > +	int res;
> > > > +
> > > > +	addr = yt922x_sds_phyaddr_get(port,
> > > > +				      YT922X_PHY_REG_TYPE_SDS_COMMON_EXT,
> > > > +				      YT922X_PHY_REG_SPACE_SGMII);
> > > > +	if (addr < 0)
> > > > +		return -EINVAL;
> > > > +	/* write protect */
> > > > +	res = yt921x_intif_ext_write(priv, addr, 0x4be, 0xd);
> > > > +	if (res)
> > > > +		return res;
> > > > +	/* CDR */
> > > > +	if (interface == PHY_INTERFACE_MODE_100BASEX) {
> > > > +		res = yt921x_intif_ext_write(priv, addr, 0x406, 0x0);
> > > > +		if (res)
> > > > +			return res;
> > > > +		res = yt921x_intif_ext_write(priv, addr, 0x416, 0x3458);
> > > > +		if (res)
> > > > +			return res;
> > > > +	} else {
> > > > +		res = yt921x_intif_ext_write(priv, addr, 0x406, 0x800);
> > > > +		if (res)
> > > > +			return res;
> > > > +		res = yt921x_intif_ext_write(priv, addr, 0x416, 0x4558);
> > > > +		if (res)
> > > > +			return res;
> > > > +	}
> > > > +	/* PLL */
> > > > +	if (interface == PHY_INTERFACE_MODE_USXGMII) {
> > > > +		res = yt921x_intif_ext_write(priv, addr, 0x43a, 0x1006);
> > > > +		if (res)
> > > > +			return res;
> > > > +		res = yt921x_intif_ext_write(priv, addr, 0x43f, 0x3029);
> > > > +		if (res)
> > > What is this function doing?
> > Ans: Complete some init configuration according to serdes interface mode.
> Sorry, missed this email until today.
>
> Which SERDES? The switches SERDES, or the PHY SERDES.
>
> We normally refer to the switch SERDES as a PCS, and have a PCS driver
> for it. Sometimes you also need a generic PHY. Please look around at
> other devices and understand the architecture.
>
> The PHYs SERDES interface is configured by the PHY driver. The MAC
> driver should never touch PHY registers. Same as the PHY driver should
> never touch MAC registers.

Ans: Okay, this is the switch SerDes. We will refer to the existing

implementation and modify the code logic accordingly

>         Andrew