Inconsistency with HDMI Displays

dleberfinger · June 23, 2025, 1:01pm

I have two displays from Riverdi that I am currently trying to test. I am using a Mallow Board with an IMX8M Plus Quad 4GB. I am using an Avalonia Frame Buffer project.

These are the 2 displays, I would expect them to work exactly the same given the size is the only difference I am aware of:
SM-RVT50HQHNWC00-B
SM-RVT70HQHNWC00-B

I can get my project to display on the 7" screen without issue, however when I try the same steps for the 5" display I get power to the screen, but my project will not display on it nor will Tezi display on it. I do have the HDMI overlay applied. Any assistance or directions to look for a solution would be appreciated. I’ve also tested this program on the 10.1" LVDS display without issue.

Software summary
------------------------------------------------------------
Bootloader:               U-Boot
Kernel version:           6.6.84-7.2.0-g87bfb710b6f1 #1-Torizon SMP PREEMPT Mon Mar 31 08:47:48 UTC 2025
Kernel command line:      root=LABEL=otaroot rootfstype=ext4 quiet logo.nologo vt.global_cursor_default=0 plymouth.ignore-serial-consoles splash fbcon=map:3 ostree=/ostree/boot.1/torizon/157a467dd3b97eaebfbf6e17d0c8859fdd0abc1d397c637c6ecd808f79dc0260/0
Distro name:              NAME="Torizon OS"
Distro version:           VERSION_ID=7.2.0-build.13
Distro variant:           VARIANT="Docker"
Hostname:                 verdin-imx8mp-15646703
------------------------------------------------------------

Hardware info
------------------------------------------------------------
HW model:                 Toradex Verdin iMX8M Plus WB on Verdin Development Board
Toradex version:          0058 V1.1B
Serial number:            15646703
Processor arch:           aarch64
------------------------------------------------------------

torizon@verdin-imx8mp-15646703:~$ dmesg | grep hdmi
[    0.046135] /soc@0/bus@30c00000/lcd-controller@32fc6000: Fixed dependency cycle(s) with /soc@0/bus@30c00000/hdmi@32fd8000
[    0.046228] /soc@0/bus@30c00000/hdmi@32fd8000: Fixed dependency cycle(s) with /soc@0/bus@30c00000/lcd-controller@32fc6000
[    0.048441] /soc@0/bus@30000000/pinctrl@30330000: Fixed dependency cycle(s) with /soc@0/bus@30000000/pinctrl@30330000/hdmihoggrp
[    0.061826] /soc@0/bus@30c00000/lcd-controller@32fc6000: Fixed dependency cycle(s) with /soc@0/bus@30c00000/hdmi@32fd8000
[    0.061926] /soc@0/bus@30c00000/hdmi@32fd8000: Fixed dependency cycle(s) with /soc@0/bus@30c00000/lcd-controller@32fc6000
[    0.064127] /soc@0/bus@30c00000/lcd-controller@32fc6000: Fixed dependency cycle(s) with /soc@0/bus@30c00000/hdmi@32fd8000
[    0.064488] /soc@0/bus@30c00000/lcd-controller@32fc6000: Fixed dependency cycle(s) with /soc@0/bus@30c00000/hdmi@32fd8000
[    0.064588] /soc@0/bus@30c00000/hdmi@32fd8000: Fixed dependency cycle(s) with /soc@0/bus@30c00000/lcd-controller@32fc6000
[    6.410941] dwhdmi-imx 32fd8000.hdmi: Detected HDMI TX controller v2.13a with HDCP (samsung_dw_hdmi_phy2)
[    6.412410] dwhdmi-imx 32fd8000.hdmi: registered DesignWare HDMI I2C bus driver
[    6.417319] imx-drm display-subsystem: bound 32fd8000.hdmi (ops dw_hdmi_imx_ops)
[    8.969278] input: audio-hdmi HDMI Jack as /devices/platform/sound-hdmi/sound/card0/input4

ToradexAI · June 23, 2025, 1:02pm

Hi, I’m the Toradex AI Assistant.

I might make mistakes. Our support team will step in if needed. If I answered your question, please tick the “Solution” checkbox. For follow-up questions to me, please use @ToradexAI in your post.

Did you like my answer?

Hello! Thank you for providing such detailed information about your setup and the issue you’re facing.

From your description, the 7" and 10.1" displays work, but the 5" Riverdi display only powers up (backlight on) without any visible output, even with Toradex Easy Installer (Tezi) and the HDMI overlay applied. Since both displays are similar and you’re using the same configuration, let’s troubleshoot step by step:

1. Check if Linux Detects the Display (EDID)

The first step is to verify whether the 5" display is detected by the system and whether its EDID (Extended Display Identification Data) is being read properly.

Please run this command with the 5" display connected and share the output:

find /sys/devices -name "edid"

Then, you can check the content of the EDID file (replace <path-to-edid> with the actual path, e.g. /sys/class/drm/card0-HDMI-A-1/edid):

hexdump -C <path-to-edid>

If the EDID file is missing or empty, it indicates that the display is not communicating its capabilities to the HDMI controller, which can prevent graphics output.

2. Confirm Display Settings

Check the default resolution and supported timings of the 5" Riverdi display in its datasheet. The default resolution for HDMI on Verdin iMX8M Plus is 1920x1080 (reference). Many small panels may not advertise or accept this mode by default.

3. Use a Custom Display Configuration

If the 5" display does not support 1920x1080 or has specific timing requirements, you may need to force a supported mode.

With TorizonCore, you can customize the display settings for Weston. Edit (or create) the weston.ini file in your deployment, for example:

[output]
name=HDMI-A-1
mode=preferred

Or, manually set the mode:

[output]
name=HDMI-A-1
mode=800x480

Replace 800x480 with the native resolution of your 5" display.

How to do this and more is described here:
Working with Weston on TorizonCore: Customization

4. Compare dmesg / journalctl Output

Check for lines related to HDMI or DRM in dmesg or journalctl and look for errors or warnings when you plug in the 5" display compared to the 7".

5. Physical Layer Check

While avoiding hardware modifications as per guidelines, ensure that your HDMI cable and connection are properly seated and compatible with both displays.

Summarized Steps:

Check EDID readout and compare between the 5" and 7" displays.
Ensure the 5" display supports the default output resolution; if not, force the correct mode in weston.ini.
Review display setup documentation for additional insights.
Capture and review kernel boot log differences for both displays.

Let me know the results of the EDID and mode changes, and we can proceed from there.

Best regards,
Toradex AI Assistant.

dleberfinger · June 23, 2025, 1:54pm

I think I had some misconceptions about how the native HDMI output worked with Avalonia and Frame Buffer. I just needed to manually set my resolution using this command to get my display to work properly.

sudo fw_setenv tdxargs video=HDMI-A-1:800x480