Changing Boot Logo in U-Boot

This guide explains how to load and display a custom boot logo in U-Boot on the target machine. You can load the splash screen from different storage devices, such as MMC/SD, USB, or use a preloaded image stored in the U-Boot binary.

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Prerequisites

Before proceeding, ensure that you have access to U-Boot mode on the Mecha Comet device. To do this, follow the steps outlined here:

Booting into Uboot

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1. Loading and Displaying a Boot Logo in U-Boot

1.1 Loading from MMC/SD Card

To load a BMP image from an MMC/SD card:

$ mmc dev 0          # Select MMC/SD card
$ mmc rescan         # Rescan for storage devices
$ load mmc 0 ${loadaddr} <bmp file name>  # Load BMP file into memory
$ bmp display ${loadaddr}  # Display the image

Example:

$ mmc dev 2
$ mmc rescan
$ load mmc 2 ${loadaddr} splash/logo.bmp
$ bmp display ${loadaddr}

1.2 Loading from USB Storage

To load a BMP image from a USB storage device:

$ usb start          # Start USB subsystem
$ load usb <device number> ${loadaddr} <bmp file name>  # Load BMP file
$ bmp display ${loadaddr}  # Display the image

Example:

$ usb start
$ load usb 0 ${loadaddr} splash/logo.bmp
$ bmp display ${loadaddr}

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2. Preloading Splash Screen from eMMC/SD/USB

Instead of embedding the splash screen in the U-Boot binary, you can configure U-Boot to automatically load the logo from a FAT partition on an eMMC, SD card, or USB storage.

2.1 Setting Up Automatic Splash Screen Loading

To configure U-Boot to load a splash screen automatically:

1. Ensure the splash screen file is stored in a FAT partition.
2. Set the splashfile variable to point to the splash screen image.
3. Set the splashsource variable to specify the storage device.
4. Save the environment variables.
5. Restart the system.

$ setenv splashfile /boot/logo.bmp  # Set splash screen file path
$ setenv splashsource mmc_fs        # Specify source storage (e.g., mmc_fs, usb_fs)
$ saveenv                            # Save environment settings
$ reset                              # Reboot to apply changes

Example for eMMC:

$ setenv splashfile /boot/logo.bmp
$ setenv splashsource mmc_fs
$ saveenv
$ reset

Example for USB:

$ setenv splashfile /boot/logo.bmp
$ setenv splashsource usb_fs
$ saveenv
$ reset

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3. Additional Notes

• Ensure that the BMP file is in a compatible format (e.g., 24-bit uncompressed BMP).
• loadaddr should be set to a valid memory address where the image will be loaded.
• Use printenv to check current environment variables.
• If the splash screen does not appear, check the storage device and file path.

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Conclusion

This guide provides a step-by-step approach to changing the boot logo in U-Boot using different methods. Depending on your use case, you can either load the logo manually or configure it for automatic loading during boot.