Re: [PATCH net-next v3 4/4] net: dp83869: Add RGMII internal delay configuration

[Dan Murphy]

Andrew

On 5/27/20 8:12 AM, Andrew Lunn wrote:
> > If the dt defines rgmii-rx/tx-id then these values are required not
> > optional. That was the discussion on the binding.
> How many times do i need to say it. They are optional. If not
> specified, default to 2ns.

OK. I guess then the DP83867 driver is wrong because it specifically 
states in bold

ÂÂÂ /* RX delay *must* be specified if internal delay of RX is used. */

It was signed off in commit fafc5db28a2ff


> > > > +	ret = of_property_read_u32(of_node, "tx-internal-delay-ps",
> > > > +				   &dp83869->tx_id_delay);
> > > > +	if (ret) {
> > > > +		dp83869->tx_id_delay = ret;
> > > > +		ret = 0;
> > > > +	}
> > > > +
> > > >    	return ret;
> > > >    }
> > > >    #else
> > > > @@ -367,10 +388,45 @@ static int dp83869_configure_mode(struct phy_device *phydev,
> > > >    	return ret;
> > > >    }
> > > > +static int dp83869_get_delay(struct phy_device *phydev)
> > > > +{
> > > > +	struct dp83869_private *dp83869 = phydev->priv;
> > > > +	int delay_size = ARRAY_SIZE(dp83869_internal_delay);
> > > > +	int tx_delay = 0;
> > > > +	int rx_delay = 0;
> > > > +
> > > > +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
> > > > +	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) {
> > > > +		tx_delay = phy_get_delay_index(phydev,
> > > > +					       &dp83869_internal_delay[0],
> > > > +					       delay_size, dp83869->tx_id_delay,
> > > > +					       false);
> > > > +		if (tx_delay < 0) {
> > > > +			phydev_err(phydev, "Tx internal delay is invalid\n");
> > > > +			return tx_delay;
> > > > +		}
> > > > +	}
> > > > +
> > > > +	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> > > > +	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID) {
> > > > +		rx_delay = phy_get_delay_index(phydev,
> > > > +					       &dp83869_internal_delay[0],
> > > > +					       delay_size, dp83869->rx_id_delay,
> > > > +					       false);
> > > > +		if (rx_delay < 0) {
> > > > +			phydev_err(phydev, "Rx internal delay is invalid\n");
> > > > +			return rx_delay;
> > > > +		}
> > > > +	}
> > > So any PHY using these properties is going to pretty much reproduce
> > > this code. Meaning is should all be in a helper.
> > The issue here is that the phy_mode may only be rgmii-txid so you only want
> > to find the tx_delay and return.
> >
> > Same with the RXID. How is the helper supposed to know what delay to return
> > and look for?
> How does this code do it? It looks at the value of interface.

Actually I will be removing this check with setting the delays to default.

Dan


>      Andrew