net: phy: dp83867: allow RGMII_TXID/RGMII_RXID interface types

Currently dp83867 driver returns error if phy interface type
PHY_INTERFACE_MODE_RGMII_RXID is used to set the rx only internal
delay. Similarly issue happens for PHY_INTERFACE_MODE_RGMII_TXID.
Fix this by checking also the interface type if a particular delay
value is missing in the phy dt bindings. Also update the DT document
accordingly.

Signed-off-by: Murali Karicheri <[e-mail]>
Signed-off-by: Sekhar Nori <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/devicetree/bindings/net/ti,dp83867.txt

···
 Required properties:
 	- reg - The ID number for the phy, usually a small integer
 	- ti,rx-internal-delay - RGMII Receive Clock Delay - see dt-bindings/net/ti-dp83867.h
-		for applicable values
+		for applicable values. Required only if interface type is
+		PHY_INTERFACE_MODE_RGMII_ID or PHY_INTERFACE_MODE_RGMII_RXID
 	- ti,tx-internal-delay - RGMII Transmit Clock Delay - see dt-bindings/net/ti-dp83867.h
-		for applicable values
+		for applicable values. Required only if interface type is
+		PHY_INTERFACE_MODE_RGMII_ID or PHY_INTERFACE_MODE_RGMII_TXID
 	- ti,fifo-depth - Transmitt FIFO depth- see dt-bindings/net/ti-dp83867.h
 		for applicable values
 

drivers/net/phy/dp83867.c

···
 
 	ret = of_property_read_u32(of_node, "ti,rx-internal-delay",
 				   &dp83867->rx_id_delay);
-	if (ret)
+	if (ret &&
+	    (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	     phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID))
 		return ret;
 
 	ret = of_property_read_u32(of_node, "ti,tx-internal-delay",
 				   &dp83867->tx_id_delay);
-	if (ret)
+	if (ret &&
+	    (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	     phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID))
 		return ret;
 
 	return of_property_read_u32(of_node, "ti,fifo-depth",