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, 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