What:		/sys/class/mdio_bus/<bus>/<device>/attached_dev
Date:		May 2017
KernelVersion:	4.13
Contact:	netdev@vger.kernel.org
Description:
		Symbolic link to the network device this PHY device is
		attached to.

What:		/sys/class/mdio_bus/<bus>/<device>/phy_has_fixups
Date:		February 2014
KernelVersion:	3.15
Contact:	netdev@vger.kernel.org
Description:
		This attribute contains the boolean value whether a given PHY
		device has had any "fixup" workaround running on it, encoded as
		a boolean. This information is provided to help troubleshooting
		PHY configurations.

What:		/sys/class/mdio_bus/<bus>/<device>/phy_id
Date:		November 2012
KernelVersion:	3.8
Contact:	netdev@vger.kernel.org
Description:
		This attribute contains the 32-bit PHY Identifier as reported
		by the device during bus enumeration, encoded in hexadecimal.
		This ID is used to match the device with the appropriate
		driver.

What:		/sys/class/mdio_bus/<bus>/<device>/c45_phy_ids/mmd<n>_device_id
Date:		June 2025
KernelVersion:	6.17
Contact:	netdev@vger.kernel.org
Description:
		This attribute contains the 32-bit PHY Identifier as reported
		by the device during bus enumeration, encoded in hexadecimal.
		These C45 IDs are used to match the device with the appropriate
		driver. These files are invisible to the C22 device.

What:		/sys/class/mdio_bus/<bus>/<device>/phy_interface
Date:		February 2014
KernelVersion:	3.15
Contact:	netdev@vger.kernel.org
Description:
		This attribute contains the PHY interface as configured by the
		Ethernet driver during bus enumeration, encoded in string.
		This interface mode is used to configure the Ethernet MAC with the
		appropriate mode for its data lines to the PHY hardware.

		Possible values are:

		<empty> (not available), mii, gmii, sgmii, tbi, rev-mii,
		rmii, rgmii, rgmii-id, rgmii-rxid, rgmii-txid, rtbi, smii
		xgmii, moca, qsgmii, trgmii, 1000base-x, 2500base-x, rxaui,
		xaui, 10gbase-kr, unknown

What:		/sys/class/mdio_bus/<bus>/<device>/phy_standalone
Date:		May 2019
KernelVersion:	5.3
Contact:	netdev@vger.kernel.org
Description:
		Boolean value indicating whether the PHY device is used in
		standalone mode, without a net_device associated, by PHYLINK.
		Attribute created only when this is the case.

What:		/sys/class/mdio_bus/<bus>/<device>/phy_dev_flags
Date:		March 2021
KernelVersion:	5.13
Contact:	netdev@vger.kernel.org
Description:
		32-bit hexadecimal number representing a bit mask of the
		configuration bits passed from the consumer of the PHY
		(Ethernet MAC, switch, etc.) to the PHY driver. The flags are
		only used internally by the kernel and their placement are
		not meant to be stable across kernel versions. This is intended
		for facilitating the debugging of PHY drivers.