Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 2/14/2023
Public

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16.5.12.6.2. Discovering Removable MMC4.3 Boot Mode Support

For removable MMC4.3 cards, the software driver must perform the following steps:
  1. Discover the card as described in Enumerated Card Stack.
  2. Read the MMC card device’s EXT_CSD registers and examine the following fields:
    • BOOT_PARTITION_ENABLE
    • BOOT_SIZE_MULT
    • BOOT_INFO
    Note: For more information, refer to "Access to Boot Partition” in JEDEC Standard No. JESD84‑A43, available on the JEDEC website.
  3. If the host processor needs to perform a boot operation at the next power‑up cycle, it can manipulate the contents of the EXT_CSD registers in the MMC card device, by using a SWITCH_FUNC command.
  4. After this step, the software driver must power down the card by writing to the pwren register.
  5. From here on, use the same steps as in Alternative Boot Operation for eMMC Card Devices.
    Note: Ignore the EBE if it is generated during an abort scenario.

    If a boot acknowledge error occurs, the boot acknowledge received interrupt times out.

    In internal DMA controller mode, the application needs to depend on the descriptor close interrupt instead of the data done interrupt.