Merge branch 'fix-RTL8211F-TX-delay-handling'

Martin Blumenstingl says:

====================
net: phy: realtek: fix RTL8211F TX-delay handling

The RTL8211F PHY driver currently enables the TX-delay only when the
phy-mode is PHY_INTERFACE_MODE_RGMII. This is incorrect, because there
are three RGMII variations of the phy-mode which explicitly request the
PHY to enable the RX and/or TX delay, while PHY_INTERFACE_MODE_RGMII
specifies that the PHY should disable the RX and/or TX delays.

Additionally to the RTL8211F PHY driver change this contains a small
update to the phy-mode documentation to clarify the purpose of the
RGMII phy-modes.
While this may not be perfect yet it's at least a start. Please feel
free to drop this patch from this series and send an improved version
yourself.

These patches are the results of recent discussions, see [0]

[0] http://lists.infradead.org/pipermail/linux-amlogic/2016-November/001688.html
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/ethernet.txt

@@ -9,10 +9,26 @@ The following properties are common to the Ethernet controllers:
 - max-speed: number, specifies maximum speed in Mbit/s supported by the device;
 - max-frame-size: number, maximum transfer unit (IEEE defined MTU), rather than
   the maximum frame size (there's contradiction in ePAPR).
-- phy-mode: string, operation mode of the PHY interface; supported values are
-  "mii", "gmii", "sgmii", "qsgmii", "tbi", "rev-mii", "rmii", "rgmii", "rgmii-id",
-  "rgmii-rxid", "rgmii-txid", "rtbi", "smii", "xgmii", "trgmii"; this is now a
-  de-facto standard property;
+- phy-mode: string, operation mode of the PHY interface. This is now a de-facto
+  standard property; supported values are:
+  * "mii"
+  * "gmii"
+  * "sgmii"
+  * "qsgmii"
+  * "tbi"
+  * "rev-mii"
+  * "rmii"
+  * "rgmii" (RX and TX delays are added by the MAC when required)
+  * "rgmii-id" (RGMII with internal RX and TX delays provided by the PHY, the
+     MAC should not add the RX or TX delays in this case)
+  * "rgmii-rxid" (RGMII with internal RX delay provided by the PHY, the MAC
+     should not add an RX delay in this case)
+  * "rgmii-txid" (RGMII with internal TX delay provided by the PHY, the MAC
+     should not add an TX delay in this case)
+  * "rtbi"
+  * "smii"
+  * "xgmii"
+  * "trgmii"
 - phy-connection-type: the same as "phy-mode" property but described in ePAPR;
 - phy-handle: phandle, specifies a reference to a node representing a PHY
   device; this property is described in ePAPR and so preferred;

drivers/net/phy/realtek.c

@@ -102,15 +102,19 @@ static int rtl8211f_config_init(struct phy_device *phydev)
 	if (ret < 0)
 		return ret;
 
-	if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
-		/* enable TXDLY */
 	phy_write(phydev, RTL8211F_PAGE_SELECT, 0xd08);
 	reg = phy_read(phydev, 0x11);
+
+	/* enable TX-delay for rgmii-id and rgmii-txid, otherwise disable it */
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
 		reg |= RTL8211F_TX_DELAY;
+	else
+		reg &= ~RTL8211F_TX_DELAY;
+
 	phy_write(phydev, 0x11, reg);
 	/* restore to default page 0 */
 	phy_write(phydev, RTL8211F_PAGE_SELECT, 0x0);
-	}
 
 	return 0;
 }