Vybrid Silent U-Boot? U-Boot fiddling with devices behind the scenes?

[jackblather]

I have a custom board that is based on the Vybrid Tower. Running U-Boot 2013.07 I have two issues:

1) I need U-boot to shut up. How does one do this?

2) U-boot seems to be fiddling with a device when it's just sitting at the command prompt.

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First issue: "1) I need U-boot to shut up. How does one do this?":::::

I tried:

- Changing CONFIG_SYS_UART_PORT in include/configs/vf610.h from "(1)" to another port (e.g. "(2)" ). No joy, Output still goes to UART1. This #define has no effect.

- Doing the suggestions in README.silent. No joy.

- Changing the "stdout" env var in U-Boot to a random string. I get an error when I do this.

- Setting the "silent" env var. No joy.

I may also need to prevent U-Boot from initializing the UART. How does one do this? Is there a 'hidden' #define that I need to know about?

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Second issue "2) U-boot seems to be fiddling with some devices when it's just sitting at the command prompt":::::

It looks like something is changing settings on the port PTA7 (on pin v15) after our MQX/M4 application has been launched and running. We have to set that port back to its correct value every once in a while.

I understand that U-boot does not use interrupts at all, is this true?

If U-boot does indeed have something that runs periodically via an IRQ), then that could be the culprit.

[jackblather]

I found out about the WFE and WFI instructions which are easily used via the __wfi() and __wfe() C calls. I'm able to use a small loop that is launched on the A5 from U-boot. So maybe the mysterious entity tapping on port PTA7 will go away...

[timesyssupport · Accepted solution]

Hello Jack,

My apologies for the delayed response. I was able to acheive a partial U-Boot silence by enabling the following macros in my U-Boot board config header:

#define CONFIG_SILENT_CONSOLE

#define CONFIG_SYS_DEVICE_NULLDEV

#define CONFIG_SILENT_CONSOLE_UPDATE_ON_RELOC

#define CONFIG_SILENT_U_BOOT_ONLY //optional; only silences U-Boot output, not Linux output.

Then, set the 'silent' variable in the U-Boot environment:

=> setenv silent 1

=> saveenv

Now, when the board resets, U-Boot output stops here:

U-Boot 2013.07 (Dec 01 2014 - 12:12:13)

CPU:   Freescale Vybrid 600 family rev1.1 at 396 MHz

Reset cause: EXTERNAL RESET

Board: TWR-VF65GS10

DRAM:  128 MiB

WARNING: Caches not enabled

NAND:  256 MiB

MMC:   FSL_SDHC: 0

Thanks,

Timesys Support

[jackblather]

Thank you. That will be a big help.

[karina_valencia]

timesyssupport do you have an update?

[karina_valencia]

Timesys Support any update?

[jackblather]

Oh, by the way, the MQX application is running on the M4 and we do not want anything running on the A5 when the M4 boots. We will be running Timesys Linux on the A5 later. So not only do we need U-Boot to be silent, we also need the A5 side to power down, or go into low power mode, or run a little looping program.

Boot device is the SD card.

[karina_valencia]

timesyssupport can you help to attend this case?