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RTOS/AM3354: Error during initialization PHY, AM3354

Krasnov Vitalii
Prodigy 190 points
Part Number: AM3354


Tool/software: TI-RTOS

Hello.
In our project on AM3354 we faced the following problem.
We initialize the CPSW module. During initialization of the CPSW, the MDIO module accesses the PHY chip using the MDIOPhyRegRead function. Due to the fact that in the MDIO USERACCESS0 register, the GO bit is not set to 0, the MDIOPhyRegRead function remains in an infinite loop.
To solve this problem, we made these functions with a finite number of cycles (10000), and after passing the cycle, we check the GO bit to 0. If this bit is 0, then everything is fine, otherwise we set an error.
Questions:
1. Are we doing the right thing replacing infinite loops with finite ones?
2. Why the GO bit is not reset to 0, is the cause of the failure of the PHY?

Respectfully,
Vitali

  • 0
    TI__Guru* 95265 points

    Hi,

    Once the MDIO module is enabled, the MDIO interface state machine continuously polls the PHY link status (by reading the generic status register) of all possible 32 PHY addresses and records the results in the MDIO PHY alive status register (ALIVE) and MDIO PHY link status register (LINK). The corresponding bit for the connected PHY (0-31) is set in ALIVE, if the PHY responded to the read request. The corresponding bit is set in LINK, if the PHY responded and also is currently linked. MDIO clock is typically 1-2 MHz.

    From AM335x TRM, 14.3.8.2 Functional Description. You need to wait GO bit in the MDIOUSERACCESSn registers transitions from 1 to 0, indicating the completion of a user access.You can't set this as a limit number.

    Also, see the:

    14.4.3 Initializing the MDIO Module
    14.4.4 Writing Data to a PHY Register
    14.4.5 Reading Data from a PHY Register

    The source code can be found from pdk_am335x_1_0_14\packages\ti\starterware\dal\mdio.c. If you can't see the GO bit transitting from 1 to 0, there is a problem.

    Regards, Eric

  • 0 in reply to lding
    Prodigy 190 points

    Can you suggest a possible reason why the GO bit is not reset?

    Respectfully,

    Vitalii