iMX6 Boot type change using Software Reset

[skuzu]

Hello,

We are using iMX6 Dual Lite on our board. For the boot we have 2 options, both are working fine:

1) SD card boot.

2) NOR Flash boot.

There is a Push-button connected to BOOT_CFG1[6] which selects between SD Card boot or NOR Flash Boot and we can select the between the 2 boot options no problem. But we have to do a Power cycle to select between the 2 boot options. We want to have a Software Reset, not a Power cycle to change the boot type.  

We tried Watch Dog reset, both Cold & Warm reset but couldn't make the boot type selection change. We always have to do a Power cycle to change the boot type.

Is there a Software controlled Reset to change the iMX6 boot type?

regards,

Selcuk

[CarlosCasillas]

Hi Selcuk,

According with i.MX6 Reference Manual, the selection of the interface to boot is selected by the ROM code, which is automatically executed after a POR. So, if any other reset sends the processor to start the execution after ROM code, the boot interface will not change. Therefore, it is required to restart the execution of the ROM code in order to select a different boot interface.

Hope this will be useful for you
Best regards!
/Carlos
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[skuzu]

Thanks Biyong Sun.

"bmode" was not exact fit for our application, but helped us to find out un-documented registers for a solution.

Here is the description of what we have done:

- SRC_SBMR1 register reflects the status of Boot Mode Pins :

          BOOT_CFG4[7:0],  BOOT_CFG3[7:0],  BOOT_CFG2[7:0],  BOOT_CFG1[7:0]

- At reset, if SRC_GPR10[28] is 0, SRC_SBMR1 will determine the boot device, which are driven by Boot Mode Pins.

- At reset, if SRC_GPR10[28] is 1, ROM will use SRC_GPR9 as Boot Config values. (not the SRC_SBMR1 values)

By changing SRC_GPR9 & 10 registers, we can choose the Boot mode by Soft Reset.

Selcuk

[BiyongSUN]

There is "bmode" command in uboot. Please refer to the 3.10.xx or 3.14.xx release.