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AM3352: Booting from eMMC boot partition

Christoph
Intellectual 720 points

Part Number: AM3352

Hello,

i am using a Custom Board with the Sitara AM3352 and a connected eMMC Memory from Micron.

Booting without the alternative Boot Method works fine (data is stored in /dev/mmcblk0).

The eMMC is equipped with two boot partitions and my goal is to boot from one of these partitions.

So I want to boot my MLO, and later u-boot image, from emmc boot partiton /dev/mmcblk0boot0.

According to MMC ver. 4.3 I have to set  some fields in EXT_CSD register for emmc.

This fields I set for the /dev/mmcblk0boot0 device.

PARTITION_CONFIG [179] = 0x48 (BOOT_ACK=0x1, BOOT_PARTITION_ENABLE=0x1)

-->Boot Partition 1 enabled, No access to boot partition and enable booting partition boot0.

BOOT_BUS_CONDITIONS [177] = 0x12 or 0x16

--> ddr mode

RST_N_FUNCTION [162] = 0x01 or 0x0

--> with/without reset function

Then, I copied my MLO with the dd command to /dev/mmcblk0boot0.

I also tried creating a partition on the device and copied the files into the partition.

Nothing from the above versions could get me the MLO booting.

Do I need to set something in the SD_CON Register?

(BOOT_ACK, BOOT_CF0, ...)

What am I missing?

Anything else I need to set or do?

Thx for the help!

Greetings

Christoph

  • 0
    TI__Genius 15510 points
    The boot ROM in the AM335x processors does not support booting from the boot partitions. What are your sysboot settings?

    Steve K.
  • 0 in reply to Steve Kipisz
    Intellectual 720 points
    Hello Steve,

    thx for the quick reply!


    AM3352 datasheet is saying 'Complies with MMC4.3'.
    This is not enough to support boot partitions?


    The boot sequence for the CPU is defined from the circuit design.
    MMC1 first, then MMC0, ...

    Are the sysboot setting something special from the Evaluation Boards?
    If not, where can I find my settings?


    The strange thing is I thought I had the MLO booting from the boot partition for once.
    But I could not do it a second time after I tried booting the second U-Boot stage as well.


    Thx for the help!

    Best regards
    Christoph
  • 0 in reply to Christoph
    TI__Genius 15510 points
    The boot ROM does not support booting from the boot partition.

    The sysboot pins control the boot order. See table 26-7 in the TRM. The only boot devices available are in this table, and booting from the boot partition is not in there. The only TI processor that boots from the boot partition is AM57xx. You can read the control status register that will tell you how the pins are set. From u-boot, do md.l 0x444e10040. The default for BBB is 0x0040033c. So from the TRM, the boot order is
    mmc1 -> mmc0 -> uart0 -> usb0

    Steve K.