[PATCH net-next v5 0/3] net: phy: dp83822: Add support for changing the transmit amplitude voltage

[PATCH net-next v5 0/3] net: phy: dp83822: Add support for changing the transmit amplitude voltage

[Dimitri Fedrau via B4 Relay]

Add support for changing the transmit amplitude voltage in 100BASE-TX mode.
Add support for configuration via DT.

Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
---
Changes in v5:
- Remove default from binding
- Fix description in binding by defining what 100% gain means
- Switch to reverse christmas tree in phy_get_internal_delay
- Add kernel doc for phy_get_tx_amplitude_gain
- EXPORT_SYMBOL_GPL for phy_get_tx_amplitude_gain
- Link to v4: https://lore.kernel.org/r/20250211-dp83822-tx-swing-v4-0-1e8ebd71ad54@liebherr.com

Changes in v4:
- Remove type $ref from binding
- Remove '|' from description in binding
- Change helper function from:
    static int phy_get_int_delay_property(struct device *dev, const char *name)
  to:
    static int phy_get_u32_property(struct device *dev, const char *name, u32 *val)
- Apply helper function to phy_get_internal_delay
- Link to v3: https://lore.kernel.org/r/20250204-dp83822-tx-swing-v3-0-9798e96500d9@liebherr.com

Changes in v3:
- Switch to tx-amplitude-100base-tx-percent in bindings
- Link to v2: https://lore.kernel.org/r/20250120-dp83822-tx-swing-v2-0-07c99dc42627@liebherr.com

Changes in v2:
- Remove binding ti,tx-amplitude-100base-tx-millivolt from ti,dp83822.yaml
- Add binding tx-amplitude-100base-tx-gain-milli to ethernet-phy.yaml
- Add helper to get tx amplitude gain from DT
- Link to v1: https://lore.kernel.org/r/20250113-dp83822-tx-swing-v1-0-7ed5a9d80010@liebherr.com

---
Dimitri Fedrau (3):
      dt-bindings: net: ethernet-phy: add property tx-amplitude-100base-tx-percent
      net: phy: Add helper for getting tx amplitude gain
      net: phy: dp83822: Add support for changing the transmit amplitude voltage

 .../devicetree/bindings/net/ethernet-phy.yaml      |  6 +++
 drivers/net/phy/dp83822.c                          | 38 ++++++++++++++++
 drivers/net/phy/phy_device.c                       | 53 ++++++++++++++--------
 include/linux/phy.h                                |  4 ++
 4 files changed, 83 insertions(+), 18 deletions(-)
---
base-commit: 7a7e0197133d18cfd9931e7d3a842d0f5730223f
change-id: 20241213-dp83822-tx-swing-5ba6c1e9b065

Best regards,
-- 
Dimitri Fedrau <dimitri.fedrau@liebherr.com>

[PATCH net-next v5 1/3] dt-bindings: net: ethernet-phy: add property tx-amplitude-100base-tx-percent

[Dimitri Fedrau via B4 Relay]

From: Dimitri Fedrau <dimitri.fedrau@liebherr.com>

Add property tx-amplitude-100base-tx-percent in the device tree bindings
for configuring the tx amplitude of 100BASE-TX PHYs. Modifying it can be
necessary to compensate losses on the PCB and connector, so the voltages
measured on the RJ45 pins are conforming.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
---
 Documentation/devicetree/bindings/net/ethernet-phy.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
index 2c71454ae8e362e7032e44712949e12da6826070..824bbe4333b7ed95cc39737d3c334a20aa890f01 100644
--- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
@@ -232,6 +232,12 @@ properties:
       PHY's that have configurable TX internal delays. If this property is
       present then the PHY applies the TX delay.
 
+  tx-amplitude-100base-tx-percent:
+    description:
+      Transmit amplitude gain applied for 100BASE-TX. 100% matches 2V
+      peak-to-peak specified in ANSI X3.263. When omitted, the PHYs default
+      will be left as is.
+
   leds:
     type: object
 

-- 
2.39.5

Re: [PATCH net-next v5 1/3] dt-bindings: net: ethernet-phy: add property tx-amplitude-100base-tx-percent

[Andrew Lunn]

On Fri, Feb 14, 2025 at 03:14:09PM +0100, Dimitri Fedrau via B4 Relay wrote:
> From: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
> 
> Add property tx-amplitude-100base-tx-percent in the device tree bindings
> for configuring the tx amplitude of 100BASE-TX PHYs. Modifying it can be
> necessary to compensate losses on the PCB and connector, so the voltages
> measured on the RJ45 pins are conforming.
> 
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

[PATCH net-next v5 2/3] net: phy: Add helper for getting tx amplitude gain

[Dimitri Fedrau via B4 Relay]

From: Dimitri Fedrau <dimitri.fedrau@liebherr.com>

Add helper which returns the tx amplitude gain defined in device tree.
Modifying it can be necessary to compensate losses on the PCB and
connector, so the voltages measured on the RJ45 pins are conforming.

Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
---
 drivers/net/phy/phy_device.c | 53 +++++++++++++++++++++++++++++---------------
 include/linux/phy.h          |  4 ++++
 2 files changed, 39 insertions(+), 18 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 9b06ba92f2ed207ec1e254ad3d1c8111933f4181..4223742e3b0c16d782f790c2fcf9e7dbdd32ba2d 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -3096,19 +3096,12 @@ void phy_get_pause(struct phy_device *phydev, bool *tx_pause, bool *rx_pause)
 EXPORT_SYMBOL(phy_get_pause);
 
 #if IS_ENABLED(CONFIG_OF_MDIO)
-static int phy_get_int_delay_property(struct device *dev, const char *name)
+static int phy_get_u32_property(struct device *dev, const char *name, u32 *val)
 {
-	s32 int_delay;
-	int ret;
-
-	ret = device_property_read_u32(dev, name, &int_delay);
-	if (ret)
-		return ret;
-
-	return int_delay;
+	return device_property_read_u32(dev, name, val);
 }
 #else
-static int phy_get_int_delay_property(struct device *dev, const char *name)
+static int phy_get_u32_property(struct device *dev, const char *name, u32 *val)
 {
 	return -EINVAL;
 }
@@ -3133,12 +3126,12 @@ static int phy_get_int_delay_property(struct device *dev, const char *name)
 s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 			   const int *delay_values, int size, bool is_rx)
 {
-	s32 delay;
-	int i;
+	int i, ret;
+	u32 delay;
 
 	if (is_rx) {
-		delay = phy_get_int_delay_property(dev, "rx-internal-delay-ps");
-		if (delay < 0 && size == 0) {
+		ret = phy_get_u32_property(dev, "rx-internal-delay-ps", &delay);
+		if (ret < 0 && size == 0) {
 			if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
 			    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID)
 				return 1;
@@ -3147,8 +3140,8 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 		}
 
 	} else {
-		delay = phy_get_int_delay_property(dev, "tx-internal-delay-ps");
-		if (delay < 0 && size == 0) {
+		ret = phy_get_u32_property(dev, "tx-internal-delay-ps", &delay);
+		if (ret < 0 && size == 0) {
 			if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
 			    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
 				return 1;
@@ -3157,8 +3150,8 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 		}
 	}
 
-	if (delay < 0)
-		return delay;
+	if (ret < 0)
+		return ret;
 
 	if (size == 0)
 		return delay;
@@ -3193,6 +3186,30 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 }
 EXPORT_SYMBOL(phy_get_internal_delay);
 
+/**
+ * phy_get_tx_amplitude_gain - stores tx amplitude gain in @val
+ * @phydev: phy_device struct
+ * @dev: pointer to the devices device struct
+ * @linkmode: linkmode for which the tx amplitude gain should be retrieved
+ * @val: tx amplitude gain
+ *
+ * Returns: 0 on success, < 0 on failure
+ */
+int phy_get_tx_amplitude_gain(struct phy_device *phydev, struct device *dev,
+			      enum ethtool_link_mode_bit_indices linkmode,
+			      u32 *val)
+{
+	switch (linkmode) {
+	case ETHTOOL_LINK_MODE_100baseT_Full_BIT:
+		return phy_get_u32_property(dev,
+					    "tx-amplitude-100base-tx-percent",
+					    val);
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL_GPL(phy_get_tx_amplitude_gain);
+
 static int phy_led_set_brightness(struct led_classdev *led_cdev,
 				  enum led_brightness value)
 {
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 64982eba71d1eab504307cc83b9c5bbe6886ed29..ffd0eb7f7425ba3dfebbeb966c1fd83783586e08 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -2124,6 +2124,10 @@ void phy_get_pause(struct phy_device *phydev, bool *tx_pause, bool *rx_pause);
 s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 			   const int *delay_values, int size, bool is_rx);
 
+int phy_get_tx_amplitude_gain(struct phy_device *phydev, struct device *dev,
+			      enum ethtool_link_mode_bit_indices linkmode,
+			      u32 *val);
+
 void phy_resolve_pause(unsigned long *local_adv, unsigned long *partner_adv,
 		       bool *tx_pause, bool *rx_pause);
 

-- 
2.39.5

Re: [PATCH net-next v5 2/3] net: phy: Add helper for getting tx amplitude gain

[Andrew Lunn]

On Fri, Feb 14, 2025 at 03:14:10PM +0100, Dimitri Fedrau via B4 Relay wrote:
> From: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
> 
> Add helper which returns the tx amplitude gain defined in device tree.
> Modifying it can be necessary to compensate losses on the PCB and
> connector, so the voltages measured on the RJ45 pins are conforming.
> 
> Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

[PATCH net-next v5 3/3] net: phy: dp83822: Add support for changing the transmit amplitude voltage

[Dimitri Fedrau via B4 Relay]

From: Dimitri Fedrau <dimitri.fedrau@liebherr.com>

Add support for changing the transmit amplitude voltage in 100BASE-TX mode.
Modifying it can be necessary to compensate losses on the PCB and
connector, so the voltages measured on the RJ45 pins are conforming.

Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
---
 drivers/net/phy/dp83822.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/net/phy/dp83822.c b/drivers/net/phy/dp83822.c
index 6599feca1967d705331d6e354205a2485ea962f2..3662f3905d5ade8ad933608fcaeabb714a588418 100644
--- a/drivers/net/phy/dp83822.c
+++ b/drivers/net/phy/dp83822.c
@@ -31,6 +31,7 @@
 #define MII_DP83822_RCSR	0x17
 #define MII_DP83822_RESET_CTRL	0x1f
 #define MII_DP83822_MLEDCR	0x25
+#define MII_DP83822_LDCTRL	0x403
 #define MII_DP83822_LEDCFG1	0x460
 #define MII_DP83822_IOCTRL1	0x462
 #define MII_DP83822_IOCTRL2	0x463
@@ -123,6 +124,9 @@
 #define DP83822_IOCTRL1_GPIO1_CTRL		GENMASK(2, 0)
 #define DP83822_IOCTRL1_GPIO1_CTRL_LED_1	BIT(0)
 
+/* LDCTRL bits */
+#define DP83822_100BASE_TX_LINE_DRIVER_SWING	GENMASK(7, 4)
+
 /* IOCTRL2 bits */
 #define DP83822_IOCTRL2_GPIO2_CLK_SRC		GENMASK(6, 4)
 #define DP83822_IOCTRL2_GPIO2_CTRL		GENMASK(2, 0)
@@ -197,6 +201,7 @@ struct dp83822_private {
 	bool set_gpio2_clk_out;
 	u32 gpio2_clk_out;
 	bool led_pin_enable[DP83822_MAX_LED_PINS];
+	int tx_amplitude_100base_tx_index;
 };
 
 static int dp83822_config_wol(struct phy_device *phydev,
@@ -522,6 +527,12 @@ static int dp83822_config_init(struct phy_device *phydev)
 			       FIELD_PREP(DP83822_IOCTRL2_GPIO2_CLK_SRC,
 					  dp83822->gpio2_clk_out));
 
+	if (dp83822->tx_amplitude_100base_tx_index >= 0)
+		phy_modify_mmd(phydev, MDIO_MMD_VEND2, MII_DP83822_LDCTRL,
+			       DP83822_100BASE_TX_LINE_DRIVER_SWING,
+			       FIELD_PREP(DP83822_100BASE_TX_LINE_DRIVER_SWING,
+					  dp83822->tx_amplitude_100base_tx_index));
+
 	err = dp83822_config_init_leds(phydev);
 	if (err)
 		return err;
@@ -720,6 +731,11 @@ static int dp83822_phy_reset(struct phy_device *phydev)
 }
 
 #ifdef CONFIG_OF_MDIO
+static const u32 tx_amplitude_100base_tx_gain[] = {
+	80, 82, 83, 85, 87, 88, 90, 92,
+	93, 95, 97, 98, 100, 102, 103, 105,
+};
+
 static int dp83822_of_init_leds(struct phy_device *phydev)
 {
 	struct device_node *node = phydev->mdio.dev.of_node;
@@ -780,6 +796,8 @@ static int dp83822_of_init(struct phy_device *phydev)
 	struct dp83822_private *dp83822 = phydev->priv;
 	struct device *dev = &phydev->mdio.dev;
 	const char *of_val;
+	int i, ret;
+	u32 val;
 
 	/* Signal detection for the PHY is only enabled if the FX_EN and the
 	 * SD_EN pins are strapped. Signal detection can only enabled if FX_EN
@@ -815,6 +833,26 @@ static int dp83822_of_init(struct phy_device *phydev)
 		dp83822->set_gpio2_clk_out = true;
 	}
 
+	dp83822->tx_amplitude_100base_tx_index = -1;
+	ret = phy_get_tx_amplitude_gain(phydev, dev,
+					ETHTOOL_LINK_MODE_100baseT_Full_BIT,
+					&val);
+	if (!ret) {
+		for (i = 0; i < ARRAY_SIZE(tx_amplitude_100base_tx_gain); i++) {
+			if (tx_amplitude_100base_tx_gain[i] == val) {
+				dp83822->tx_amplitude_100base_tx_index = i;
+				break;
+			}
+		}
+
+		if (dp83822->tx_amplitude_100base_tx_index < 0) {
+			phydev_err(phydev,
+				   "Invalid value for tx-amplitude-100base-tx-percent property (%u)\n",
+				   val);
+			return -EINVAL;
+		}
+	}
+
 	return dp83822_of_init_leds(phydev);
 }
 

-- 
2.39.5

Re: [PATCH net-next v5 3/3] net: phy: dp83822: Add support for changing the transmit amplitude voltage

[Andrew Lunn]

On Fri, Feb 14, 2025 at 03:14:11PM +0100, Dimitri Fedrau via B4 Relay wrote:
> From: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
> 
> Add support for changing the transmit amplitude voltage in 100BASE-TX mode.
> Modifying it can be necessary to compensate losses on the PCB and
> connector, so the voltages measured on the RJ45 pins are conforming.
> 
> Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH net-next v5 0/3] net: phy: dp83822: Add support for changing the transmit amplitude voltage

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 14 Feb 2025 15:14:08 +0100 you wrote:
> Add support for changing the transmit amplitude voltage in 100BASE-TX mode.
> Add support for configuration via DT.
> 
> Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
> ---
> Changes in v5:
> - Remove default from binding
> - Fix description in binding by defining what 100% gain means
> - Switch to reverse christmas tree in phy_get_internal_delay
> - Add kernel doc for phy_get_tx_amplitude_gain
> - EXPORT_SYMBOL_GPL for phy_get_tx_amplitude_gain
> - Link to v4: https://lore.kernel.org/r/20250211-dp83822-tx-swing-v4-0-1e8ebd71ad54@liebherr.com
> 
> [...]

Here is the summary with links:
  - [net-next,v5,1/3] dt-bindings: net: ethernet-phy: add property tx-amplitude-100base-tx-percent
    https://git.kernel.org/netdev/net-next/c/7fff5d958648
  - [net-next,v5,2/3] net: phy: Add helper for getting tx amplitude gain
    https://git.kernel.org/netdev/net-next/c/961ee5aeea04
  - [net-next,v5,3/3] net: phy: dp83822: Add support for changing the transmit amplitude voltage
    https://git.kernel.org/netdev/net-next/c/4f3735e82d8a

You are awesome, thank you!
-- 
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