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NPal.2
Visitor II
January 24, 2022
Question

LAN8720 Device Tree changes

  • January 24, 2022
  • 1 reply
  • 1046 views

HI all,

We are using LAN8720 as the ethernet PHY for connectivity.

The IC has 25MHz crystal connected for the refclk and we want to run in RMII mode.

We have requirement of not using the INT_N for the ethernet IC.

Upon exploring the ST Docs I was not able to figure out the same.

What should be the correct device tree configuration for the same? We need to get it up correctly for each of TF-A , U-BOOT and Kernel ? So looking for answer around the same for device tree changes for each of these.

LAN8720 + RMII Mode + REFCLK with no using the INT_N interface.

Really appreciate the help.

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    1 reply

    P
    PatrickF
    Technical Moderator
    February 1, 2022

    Hi,

    Sound like this would be ok for you :https://wiki.st.com/stm32mpu/wiki/Ethernet_device_tree_configuration#RMII_with_Crystal_on_PHY_-28Reference_clock_-28standard_RMII_clock_name-29_is_provided_by_a_Phy_Crystal-29

    • RMII PHY with a 25MHz Crystal on it
    • Will provide 50MHz from PHY to STM32MP15 REFCLK input pin.

    For PHY_INITN pin, if not used, just forget it in the pinmux node (we don't use it on our boards, even if present on the HW).

    Maybe some more info in AN5031.

    Regards.

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