[PATCH net v4] net: phy: realtek: fix rtl8211e rx/tx delay config

[PATCH net v4] net: phy: realtek: fix rtl8211e rx/tx delay config

[Willy Liu]

There are two chip pins named TXDLY and RXDLY which actually adds the 2ns
delays to TXC and RXC for TXD/RXD latching. These two pins can config via
4.7k-ohm resistor to 3.3V hw setting, but also config via software setting
(extension page 0xa4 register 0x1c bit13 12 and 11).

The configuration register definitions from table 13 official PHY datasheet:
PHYAD[2:0] = PHY Address
AN[1:0] = Auto-Negotiation
Mode = Interface Mode Select
RX Delay = RX Delay
TX Delay = TX Delay
SELRGV = RGMII/GMII Selection

This table describes how to config these hw pins via external pull-high or pull-
low resistor.

It is a misunderstanding that mapping it as register bits below:
8:6 = PHY Address
5:4 = Auto-Negotiation
3 = Interface Mode Select
2 = RX Delay
1 = TX Delay
0 = SELRGV
So I removed these descriptions above and add related settings as below:
14 = reserved
13 = force Tx RX Delay controlled by bit12 bit11
12 = Tx Delay
11 = Rx Delay
10:0 = Test && debug settings reserved by realtek

Test && debug settings are not recommend to modify by default.

Fixes: f81dadbcf7fd ("net: phy: realtek: Add rtl8211e rx/tx delays config")
Signed-off-by: Willy Liu <willy.liu@realtek.com>
---
 drivers/net/phy/realtek.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
index 95dbe5e..0f09609 100644
--- a/drivers/net/phy/realtek.c
+++ b/drivers/net/phy/realtek.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0+
-/*
- * drivers/net/phy/realtek.c
+/* drivers/net/phy/realtek.c
  *
  * Driver for Realtek PHYs
  *
@@ -32,9 +31,9 @@
 #define RTL8211F_TX_DELAY			BIT(8)
 #define RTL8211F_RX_DELAY			BIT(3)
 
-#define RTL8211E_TX_DELAY			BIT(1)
-#define RTL8211E_RX_DELAY			BIT(2)
-#define RTL8211E_MODE_MII_GMII			BIT(3)
+#define RTL8211E_CTRL_DELAY			BIT(13)
+#define RTL8211E_TX_DELAY			BIT(12)
+#define RTL8211E_RX_DELAY			BIT(11)
 
 #define RTL8201F_ISR				0x1e
 #define RTL8201F_IER				0x13
@@ -246,16 +245,16 @@ static int rtl8211e_config_init(struct phy_device *phydev)
 	/* enable TX/RX delay for rgmii-* modes, and disable them for rgmii. */
 	switch (phydev->interface) {
 	case PHY_INTERFACE_MODE_RGMII:
-		val = 0;
+		val = RTL8211E_CTRL_DELAY | 0;
 		break;
 	case PHY_INTERFACE_MODE_RGMII_ID:
-		val = RTL8211E_TX_DELAY | RTL8211E_RX_DELAY;
+		val = RTL8211E_CTRL_DELAY | RTL8211E_TX_DELAY | RTL8211E_RX_DELAY;
 		break;
 	case PHY_INTERFACE_MODE_RGMII_RXID:
-		val = RTL8211E_RX_DELAY;
+		val = RTL8211E_CTRL_DELAY | RTL8211E_RX_DELAY;
 		break;
 	case PHY_INTERFACE_MODE_RGMII_TXID:
-		val = RTL8211E_TX_DELAY;
+		val = RTL8211E_CTRL_DELAY | RTL8211E_TX_DELAY;
 		break;
 	default: /* the rest of the modes imply leaving delays as is. */
 		return 0;
@@ -263,11 +262,12 @@ static int rtl8211e_config_init(struct phy_device *phydev)
 
 	/* According to a sample driver there is a 0x1c config register on the
 	 * 0xa4 extension page (0x7) layout. It can be used to disable/enable
-	 * the RX/TX delays otherwise controlled by RXDLY/TXDLY pins. It can
-	 * also be used to customize the whole configuration register:
-	 * 8:6 = PHY Address, 5:4 = Auto-Negotiation, 3 = Interface Mode Select,
-	 * 2 = RX Delay, 1 = TX Delay, 0 = SELRGV (see original PHY datasheet
-	 * for details).
+	 * the RX/TX delays otherwise controlled by RXDLY/TXDLY pins.
+	 * The configuration register definition:
+	 * 14 = reserved
+	 * 13 = Force Tx RX Delay controlled by bit12 bit11,
+	 * 12 = RX Delay, 11 = TX Delay
+	 * 10:0 = Test && debug settings reserved by realtek
 	 */
 	oldpage = phy_select_page(phydev, 0x7);
 	if (oldpage < 0)
@@ -277,7 +277,8 @@ static int rtl8211e_config_init(struct phy_device *phydev)
 	if (ret)
 		goto err_restore_page;
 
-	ret = __phy_modify(phydev, 0x1c, RTL8211E_TX_DELAY | RTL8211E_RX_DELAY,
+	ret = __phy_modify(phydev, 0x1c, RTL8211E_CTRL_DELAY
+			   | RTL8211E_TX_DELAY | RTL8211E_RX_DELAY,
 			   val);
 
 err_restore_page:
-- 
1.9.1

Re: [PATCH net v4] net: phy: realtek: fix rtl8211e rx/tx delay config

[David Miller]

From: Willy Liu <willy.liu@realtek.com>
Date: Tue, 29 Sep 2020 10:10:49 +0800

> There are two chip pins named TXDLY and RXDLY which actually adds the 2ns
> delays to TXC and RXC for TXD/RXD latching. These two pins can config via
> 4.7k-ohm resistor to 3.3V hw setting, but also config via software setting
> (extension page 0xa4 register 0x1c bit13 12 and 11).
> 
> The configuration register definitions from table 13 official PHY datasheet:
> PHYAD[2:0] = PHY Address
> AN[1:0] = Auto-Negotiation
> Mode = Interface Mode Select
> RX Delay = RX Delay
> TX Delay = TX Delay
> SELRGV = RGMII/GMII Selection
> 
> This table describes how to config these hw pins via external pull-high or pull-
> low resistor.
> 
> It is a misunderstanding that mapping it as register bits below:
> 8:6 = PHY Address
> 5:4 = Auto-Negotiation
> 3 = Interface Mode Select
> 2 = RX Delay
> 1 = TX Delay
> 0 = SELRGV
> So I removed these descriptions above and add related settings as below:
> 14 = reserved
> 13 = force Tx RX Delay controlled by bit12 bit11
> 12 = Tx Delay
> 11 = Rx Delay
> 10:0 = Test && debug settings reserved by realtek
> 
> Test && debug settings are not recommend to modify by default.
> 
> Fixes: f81dadbcf7fd ("net: phy: realtek: Add rtl8211e rx/tx delays config")
> Signed-off-by: Willy Liu <willy.liu@realtek.com>

Applied and queued up for -stable, thank you.