SPRAD09A December   2021  – July 2022 DRA821U , DRA821U-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1Hardware and Software Required Stuff
  4. 2DRA821U Boot Mode With Fast Boot Method
  5. 3Detailed Steps
    1. 3.1 Step1: Patch and Build/Copy the u-boot
    2. 3.2 Step2: Optimizations by Switching to xSPI Boot: Copy Bootloaders to xSPI
    3. 3.3 Step 3: Optimize the DTSI by Disabling Nodes not Mandatory for Linux Boot
    4. 3.4 Step 4: Create Bootable SD Card, Switch to TinyFS
    5. 3.5 Step 5: Switch to eMMC Filesystem
    6. 3.6 Step 6: Optimizations With Bootargs
    7. 3.7 Step 7: Hijack the init
  6. 4Debug Commands
    1. 4.1 SF Probe
    2. 4.2 mmcblk
    3. 4.3 How to Check Mounted Devices?
    4. 4.4 How to Check Your Partitions?
    5. 4.5 How to Restore Your Boot Setting?
  7. 5Fast Boot Result Review
  8. 6References
  9. 7Revision History

3 Detailed Steps

The process is broken down into seven steps. Follow the steps exactly.

  • Step1: patch and build / copy the u-boot onto your SD card “Boot Partition”.
  • Step2: Optimize boot time by switching to xSPI boot, so we copy the bootloaders from SD card onto xSPI Flash.
  • Step3: Optimize the device tree by disabling nodes not mandatory for Linux Boot.
  • Step4: Create bootable SD card, and Switch to TinyFS.
  • Step5: Switch to eMMC TinyFS filesystem (Very important step!!)
  • Step6: Optimizations with bootargs in the uboot.
  • Step7: Hijack the init.

Understand this:

  • When a brand new SD card that has never be formatted is used: Following this sequence:
    • Step4 > step1 > step2 > step3 > step5 > step6 > step7
  • If using a DRA821 bootable SD card follow the below sequence:
    • Step1 > step2 > step3 > step4 > step5 > step6 > step7

Regarding the boot switch jumper setting on the DRA821U EVM, see Table 3-1.

Table 3-1 Jacinto DRA821U EVM Boot Switch Setting
WKUP Bootmode 2 3 4 5 6 7 8 9
DIP SW9 (SW9.1) (SW9.2) (SW9.3) (SW9.4) (SW9.5) (SW9.6) (SW9.7) (SW9.8)
SD Boot (Default) OFF OFF OFF OFF OFF OFF OFF OFF
eMMC OFF ON OFF OFF OFF OFF OFF OFF
OSPI OFF ON OFF OFF OFF OFF OFF OFF
UART OFF ON ON ON OFF OFF OFF OFF
USB OFF OFF ON OFF OFF OFF OFF OFF
No Boot OFF ON ON ON OFF OFF OFF OFF
Main Bootmode 0 1 2 3 4 5 6 7
DIP SW8 (SW8.1) (SW8.2) (SW8.3) (SW8.4) (SW8.5) (SW8.6) (SW8.7) (SW8.8)
SD Boot (Default) ON OFF OFF OFF OFF OFF ON OFF
eMMC ON OFF OFF OFF OFF OFF OFF OFF
OSPI OFF OFF OFF OFF OFF ON ON OFF
UART OFF OFF OFF OFF OFF OFF OFF OFF
USB ON OFF OFF OFF OFF OFF OFF OFF
No Boot ON OFF OFF OFF ON OFF OFF OFF

There are boot switches need to be matched correctly in each step as shown above. Two boot switch settings are summarized in this document: one is the SD card switch and one is the xSPI switch.

In the step2:

  • The SD card to boot is used
  • Perform some actions that is copying the uboot onto xSPI flash.
  • Switch to the xSPI flash.

The switch setting in each step should be marked.