1What: /sys/class/mdio_bus/<bus>/<device>/attached_dev 2Date: May 2017 3KernelVersion: 4.13 4Contact: netdev@vger.kernel.org 5Description: 6 Symbolic link to the network device this PHY device is 7 attached to. 8 9What: /sys/class/mdio_bus/<bus>/<device>/phy_has_fixups 10Date: February 2014 11KernelVersion: 3.15 12Contact: netdev@vger.kernel.org 13Description: 14 This attribute contains the boolean value whether a given PHY 15 device has had any "fixup" workaround running on it, encoded as 16 a boolean. This information is provided to help troubleshooting 17 PHY configurations. 18 19What: /sys/class/mdio_bus/<bus>/<device>/phy_id 20Date: November 2012 21KernelVersion: 3.8 22Contact: netdev@vger.kernel.org 23Description: 24 This attribute contains the 32-bit PHY Identifier as reported 25 by the device during bus enumeration, encoded in hexadecimal. 26 This ID is used to match the device with the appropriate 27 driver. 28 29What: /sys/class/mdio_bus/<bus>/<device>/c45_phy_ids/mmd<n>_device_id 30Date: June 2025 31KernelVersion: 6.17 32Contact: netdev@vger.kernel.org 33Description: 34 This attribute contains the 32-bit PHY Identifier as reported 35 by the device during bus enumeration, encoded in hexadecimal. 36 These C45 IDs are used to match the device with the appropriate 37 driver. These files are invisible to the C22 device. 38 39What: /sys/class/mdio_bus/<bus>/<device>/phy_interface 40Date: February 2014 41KernelVersion: 3.15 42Contact: netdev@vger.kernel.org 43Description: 44 This attribute contains the PHY interface as configured by the 45 Ethernet driver during bus enumeration, encoded in string. 46 This interface mode is used to configure the Ethernet MAC with the 47 appropriate mode for its data lines to the PHY hardware. 48 49 Possible values are: 50 51 <empty> (not available), mii, gmii, sgmii, tbi, rev-mii, 52 rmii, rgmii, rgmii-id, rgmii-rxid, rgmii-txid, rtbi, smii 53 xgmii, moca, qsgmii, trgmii, 1000base-x, 2500base-x, rxaui, 54 xaui, 10gbase-kr, unknown 55 56What: /sys/class/mdio_bus/<bus>/<device>/phy_standalone 57Date: May 2019 58KernelVersion: 5.3 59Contact: netdev@vger.kernel.org 60Description: 61 Boolean value indicating whether the PHY device is used in 62 standalone mode, without a net_device associated, by PHYLINK. 63 Attribute created only when this is the case. 64 65What: /sys/class/mdio_bus/<bus>/<device>/phy_dev_flags 66Date: March 2021 67KernelVersion: 5.13 68Contact: netdev@vger.kernel.org 69Description: 70 32-bit hexadecimal number representing a bit mask of the 71 configuration bits passed from the consumer of the PHY 72 (Ethernet MAC, switch, etc.) to the PHY driver. The flags are 73 only used internally by the kernel and their placement are 74 not meant to be stable across kernel versions. This is intended 75 for facilitating the debugging of PHY drivers. 76