[RfC net-next 1/3] net: phy: realtek: add support for configuring the RX delay on RTL8211F

[Martin Blumenstingl <martin.blumenstingl@googlemail.com>]

On RTL8211F the RX delay can also be enabled/disabled.
The overall behavior of the RX delay is similar to the behavior of the
TX delay, which was already supported by the driver.

The RX delay (similar to the TX delay) may be enabled using hardware pin
strapping. If the MAC already configures the RX delay (if required) then
the RX delay generated by the RTL8211F PHY has to be turned off.

While here, update the comment regarding the TX delay why it has to be
enabled or disabled within the driver.
Also avoid code-duplication by extracting the code to mask/unmask bits
in a paged register into a new rtl8211x_page_mask_bits helper function.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
 drivers/net/phy/realtek.c | 55 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 45 insertions(+), 10 deletions(-)

diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
index 5416ec5af042..d4e7f249a4bc 100644
--- a/drivers/net/phy/realtek.c
+++ b/drivers/net/phy/realtek.c
@@ -32,7 +32,10 @@
 
 #define RTL8211F_INSR				0x1d
 
-#define RTL8211F_TX_DELAY			BIT(8)
+#define RTL8211F_RX_DELAY_REG			0x15
+#define RTL8211F_RX_DELAY_EN			BIT(3)
+#define RTL8211F_TX_DELAY_REG			0x11
+#define RTL8211F_TX_DELAY_EN			BIT(8)
 
 #define RTL8201F_ISR				0x1e
 #define RTL8201F_IER				0x13
@@ -74,6 +77,23 @@ static int rtl8211x_page_write(struct phy_device *phydev, u16 page,
 	return ret;
 }
 
+static int rtl8211x_page_mask_bits(struct phy_device *phydev, u16 page,
+				   u16 address, u16 mask, u16 set)
+{
+	int ret;
+	u16 val;
+
+	ret = rtl8211x_page_read(phydev, page, address);
+	if (ret < 0)
+		return ret;
+
+	val = ret & 0xffff;
+	val &= ~mask;
+	val |= (set & mask);
+
+	return rtl8211x_page_write(phydev, page, address, val);
+}
+
 static int rtl8201_ack_interrupt(struct phy_device *phydev)
 {
 	int err;
@@ -160,20 +180,35 @@ static int rtl8211f_config_init(struct phy_device *phydev)
 	if (ret < 0)
 		return ret;
 
-	ret = rtl8211x_page_read(phydev, 0xd08, 0x11);
-	if (ret < 0)
-		return ret;
+	/*
+	 * enable TX-delay for rgmii-id and rgmii-txid, otherwise disable it.
+	 * this is needed because it can be enabled by pin strapping and
+	 * conflict with the TX-delay configured by the MAC.
+	 */
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
+		val = RTL8211F_TX_DELAY_EN;
+	else
+		val = 0;
 
-	val = ret & 0xffff;
+	ret = rtl8211x_page_mask_bits(phydev, 0xd08, RTL8211F_TX_DELAY_REG,
+				      RTL8211F_TX_DELAY_EN, val);
+	if (ret)
+		return ret;
 
-	/* enable TX-delay for rgmii-id and rgmii-txid, otherwise disable it */
+	/*
+	 * enable RX-delay for rgmii-id and rgmii-rxid, otherwise disable it.
+	 * this is needed because it can be enabled by pin strapping and
+	 * conflict with the RX-delay configured by the MAC.
+	 */
 	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
-	    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
-		val |= RTL8211F_TX_DELAY;
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID)
+		val = RTL8211F_RX_DELAY_EN;
 	else
-		val &= ~RTL8211F_TX_DELAY;
+		val = 0;
 
-	ret = rtl8211x_page_write(phydev, 0xd08, 0x11, val);
+	ret = rtl8211x_page_mask_bits(phydev, 0xd08, RTL8211F_RX_DELAY_REG,
+				      RTL8211F_RX_DELAY_EN, val);
 	if (ret)
 		return ret;
 
-- 
2.15.1