U-boot default internal dtb

Technical Support
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1

Hi,
i am trying to patch u-boot lcd resolution and timing. (imx7d emmc , YOCTO and toradex 7.2.0)

Is u-boot-toradex using the dtsi with u-boot in the name
u-boot-toradex/2024.07/git/arch/arm/dts/imx7d-colibri-emmc-eval-v3-u-boot.dtsi

or only using imx7d-colibri-emmc-eval-v3.dts and its includes ?

Best Regards - Paul

2

Hi, I’m the Toradex AI Assistant.

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Hello Paul,

Thank you for your question!

On the i.MX 7D eMMC platform with Torizon/Yocto using the Toradex U-Boot (u-boot-toradex), the U-Boot build system is set up to use special device tree source include files with -u-boot.dtsi in their names when present. These files are designed to override or provide settings specific to U-Boot that differ from what the Linux kernel would need.

How this works for your board:

  • The primary device tree file for U-Boot would be imx7d-colibri-emmc-eval-v3.dts.
  • If the .dts file contains a line such as #include "imx7d-colibri-emmc-eval-v3-u-boot.dtsi" or if the build system is configured to automatically include the corresponding -u-boot.dtsi, then those settings will be applied for U-Boot only.
  • This mechanism helps maintain separation between kernel-specific and U-Boot-specific hardware settings, such as LCD timing.

To sum up:
Yes, U-Boot Toradex uses both the main .dts and, if present and included, the corresponding -u-boot.dtsi files for your i.MX7D Colibri eMMC board. You can place your LCD timing and resolution changes in either location, but placing U-Boot-specific changes in the *-u-boot.dtsi file ensures they won’t affect the Linux kernel’s device tree.

For more details:

If you need guidance with making the LCD timing patch, feel free to ask!

Best regards,
Toradex AI Assistant.

3

Hi AI
imx7d-colibri-emmc-eval-v3.dts source does not include the u-boot.dtsi unless there is a bitbake recipe changing something

– edit –
Assuming that the *u-boot.dtsi was a mistake I’ll be testing a patch of imx7d-colibri-emmc-eval-v3.dts on monday.

Regrads - Paul

4

Dear @BDSKPEF,

Thank you for sharing the hurdle you are facing with us. May I ask if the display is working otherwise? Is there simply just a resolution issue or does the display remain dark? What specific interface are you using? Is it connected via parallel RGB? Is there anything you can see during booting or in u-boot?

Best regards,
Collin

5

Hi Collin,

the display is black during u-boot , it does not show anything before the kernel splash screen.
Display is set in kernel by dtbo with same definition as the u-boot devicetree patch.
We are using the Colibri evaluation board LVDS connector.
Actually, there is no signal on LCD_PCLK_WR before the kernel splash shows.

The problem might simply relate to the discontinuation of splash support in u-boot-toradex, which i am trying to (re)configure in the u-boot .config. (Ill go through the posts related to this again :slight_smile: )

Best Regards - Paul