From 7376ba2db168c9e83f90e68f5f85c7d7f5645164 Mon Sep 17 00:00:00 2001 From: Osose Itua Date: Wed, 7 Jan 2026 17:16:52 -0500 Subject: [PATCH 1/2] dt-bindings: net: adi,adin: document LP Termination property MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add "adi,low-cmode-impedance" boolean property which, when present, configures the PHY for the lowest common-mode impedance on the receive pair for 100BASE-TX operation by clearing the B_100_ZPTM_EN_DIMRX bit. This is suited for capacitive coupled applications and other applications where there may be a path for high common-mode noise to reach the PHY. If this value is not present, the value of the bit by default is 1, which is normal termination (zero-power termination) mode. Signed-off-by: Osose Itua Acked-by: Rob Herring (Arm) Acked-by: Nuno Sá Link: https://patch.msgid.link/20260107221913.1334157-2-osose.itua@savoirfairelinux.com Signed-off-by: Jakub Kicinski --- .../devicetree/bindings/net/adi,adin.yaml | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/Documentation/devicetree/bindings/net/adi,adin.yaml b/Documentation/devicetree/bindings/net/adi,adin.yaml index c425a9f1886d..f594055c2b15 100644 --- a/Documentation/devicetree/bindings/net/adi,adin.yaml +++ b/Documentation/devicetree/bindings/net/adi,adin.yaml @@ -52,6 +52,20 @@ properties: description: Enable 25MHz reference clock output on CLK25_REF pin. type: boolean + adi,low-cmode-impedance: + description: | + Configure PHY for the lowest common-mode impedance on the receive pair + for 100BASE-TX. This is suited for capacitive coupled applications and + other applications where there may be a path for high common-mode noise + to reach the PHY. + If not present, by default the PHY is configured for normal termination + (zero-power termination) mode. + + Note: There is a trade-off of 12 mW increased power consumption with + the lowest common-mode impedance setting, but in all cases the + differential impedance is 100 ohms. + type: boolean + unevaluatedProperties: false examples: From a6733836527da97767aa7cdd2d3c6984460afdb3 Mon Sep 17 00:00:00 2001 From: Osose Itua Date: Wed, 7 Jan 2026 17:16:53 -0500 Subject: [PATCH 2/2] net: phy: adin: enable configuration of the LP Termination Register MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The ADIN1200/ADIN1300 provide a control bit that selects between normal receive termination and the lowest common mode impedance for 100BASE-TX operation. This behavior is controlled through the Low Power Termination register (B_100_ZPTM_EN_DIMRX). Bit 0 of this register enables normal termination when set (this is the default), and selects the lowest common mode impedance when cleared. Signed-off-by: Osose Itua Acked-by: Nuno Sá Link: https://patch.msgid.link/20260107221913.1334157-3-osose.itua@savoirfairelinux.com Signed-off-by: Jakub Kicinski --- drivers/net/phy/adin.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/net/phy/adin.c b/drivers/net/phy/adin.c index 7fa713ca8d45..3a934051b574 100644 --- a/drivers/net/phy/adin.c +++ b/drivers/net/phy/adin.c @@ -89,6 +89,9 @@ #define ADIN1300_CLOCK_STOP_REG 0x9400 #define ADIN1300_LPI_WAKE_ERR_CNT_REG 0xa000 +#define ADIN1300_B_100_ZPTM_DIMRX 0xB685 +#define ADIN1300_B_100_ZPTM_EN_DIMRX BIT(0) + #define ADIN1300_CDIAG_RUN 0xba1b #define ADIN1300_CDIAG_RUN_EN BIT(0) @@ -522,6 +525,19 @@ static int adin_config_clk_out(struct phy_device *phydev) ADIN1300_GE_CLK_CFG_MASK, sel); } +static int adin_config_zptm100(struct phy_device *phydev) +{ + struct device *dev = &phydev->mdio.dev; + + if (!(device_property_read_bool(dev, "adi,low-cmode-impedance"))) + return 0; + + /* clear bit 0 to configure for lowest common-mode impedance */ + return phy_clear_bits_mmd(phydev, MDIO_MMD_VEND1, + ADIN1300_B_100_ZPTM_DIMRX, + ADIN1300_B_100_ZPTM_EN_DIMRX); +} + static int adin_config_init(struct phy_device *phydev) { int rc; @@ -548,6 +564,10 @@ static int adin_config_init(struct phy_device *phydev) if (rc < 0) return rc; + rc = adin_config_zptm100(phydev); + if (rc < 0) + return rc; + phydev_dbg(phydev, "PHY is using mode '%s'\n", phy_modes(phydev->interface));