MDIO Manual Mode Enablement

Table of Contents

• Workaround for details errata i2329-MDIO interface corruption and its impact:
• Limitations
• Not supported MDIO IOCTL APIs in MDIO Manual mode

Note

If your silicon is affected with errata i2329— MDIO interface corruption, please refer to Release notes for the information [ Release Notes ], then TI suggests to use MDIO Manual mode as software workaround mentioned below

Workaround for details errata i2329-MDIO interface corruption and its impact:

• more details about errata here i2329— MDIO interface corruption.
• Workaround enforces to configure MDIO in 'MDIO_MODE_MANUAL' Mdio_Cfg::mode during Mdio_open. MDIO statemachine should not be enabled when using this workaround.
• MDIO_CLK and MDIO_IO pins are toggled using MANUAL_IF_REG registers of MDIO, using software bit-banging logic. The delays inside bit-banging logic is tuned to limit the MDIO_CLK frequency to 500 KHz.
• MDIO link change status callback (API) for application is disabled.
• Polling logic to get LINK status of active PHYs should be implemented by application, by calling EnetPhy_isLinked() API from PHY driver. Please refer to "Enet Lwip CPSW Example" and "Enet Lwip ICSSG Example" for implementation.
• Each PHY register read consumes around 100 CPU cycles as tested on AM243x platform. Which implies, polling one PHY link status at every 100 ms periodicity would take 0.1% of CPU. It scales with number of PHYs to be monitored.

Limitations

• Only Clause 22 frame format is support. Clause 45 frame format is not supported.
• MDIO state machine is disabled and hence MDIO LINK_INT and USER_INT interrupts are NOT available.
• Testing has been done by keeping "link status polling task" running at highest priority task in application.

Not supported MDIO IOCTL APIs in MDIO Manual mode

Affected API	Change
ENET_MDIO_IOCTL_GET_VERSION	Supported
ENET_MDIO_IOCTL_PRINT_REGS	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_IS_ALIVE	Supported
ENET_MDIO_IOCTL_IS_LINKED	Supported
ENET_MDIO_IOCTL_IS_POLL_ENABLED	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C22_READ	Supported
ENET_MDIO_IOCTL_C22_WRITE	Supported
ENET_MDIO_IOCTL_C45_READ	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C45_WRITE	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C22_ASYNC_READ_TRIGGER	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C22_ASYNC_READ_COMPLETE	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C22_ASYNC_WRITE_TRIGGER	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C22_ASYNC_WRITE_COMPLETE	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C45_ASYNC_READ_TRIGGER	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C45_ASYNC_READ_COMPLETE	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C45_ASYNC_WRITE_TRIGGER	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_C45_ASYNC_WRITE_COMPLETE	Not Supported if MDIO is configured in Manual Mode
MDIO_IOCTL_HANDLE_INTR	Not Supported if MDIO is configured in Manual Mode
ENET_MDIO_IOCTL_ENABLE_STATE_MACHINE	Not Supported if MDIO is configured in Manual Mode