Hello everyone,
I’m having an issue with my Raspberry Pi Compute Module 4 (CM4) where HDMI output does not display any video, despite the system booting correctly. Interestingly, this problem appeared suddenly—the HDMI output was working fine one day, and the next day it stopped.
I’ve tested this on two different I/O boards, up to five different monitors, some different PSUs (all of them 5volts, 3Amps), and with various HDMI cables, but the issue persists.
Here’s what I’ve verified so far:
The CM4 boots the OS successfully, and I can access it via OpenSSH and Windows PowerShell.
The CM4 can reproduce video internally, I've tested through a Windows app (B.Beat Manager), and I can watch video on the app. That is, video playback works within the app’s interface, so GPU and system resources appear functional.
The problem appears specifically with video output through HDMI. The connected monitor is detected (/sys/class/drm/card0-HDMI-A-1/status shows connected), and EDID is readable.
I’ve tested several configuration options in config.txt without success:
hdmi_group=1
hdmi_mode=16 # 1080p60
hdmi_enable_4kp60=1
gpu_mem=256
dtoverlay=vc4-kms-v3d
Commands tried and results:
lsmod | grep vc4 → confirms vc4-drm and associated DRM modules are loaded.
cat /sys/class/drm/card0-HDMI-A-1/modes → lists all available modes.
modetest -M vc4 → shows connector HDMI-A-1 as connected, but attempting sudo modetest -M vc4 -s 33:8 fails with failed to find mode.
sudo fbset -xres 1920 -yres 1080 -depth 24 → fails with ioctl FBIOPUT_VSCREENINFO: Invalid argument.
sudo edid-decode /sys/class/drm/card0-HDMI-A-1/edid → reads monitor EDID correctly, including 1080p60 and 4K modes.
dmesg | grep -i drm → confirms vc4-drm initialized correctly and framebuffer device vc4drmfb exists.
Observations:
The internal video playback working suggests the GPU and OS are functional.
HDMI output appears to fail during mode setting / buffer initialization (as seen with modetest and fbset).
The issue is not cable or monitor-specific.
I’m looking for guidance on:
How to get HDMI output working reliably with the CM4 on KMS/VC4 DRM.
Whether additional config.txt tweaks or overlays are required for 1080p/4K output.
Any known limitations with specific I/O boards or HDMI monitors.
Thanks in advance for any advice or guidance!
I’m having an issue with my Raspberry Pi Compute Module 4 (CM4) where HDMI output does not display any video, despite the system booting correctly. Interestingly, this problem appeared suddenly—the HDMI output was working fine one day, and the next day it stopped.
I’ve tested this on two different I/O boards, up to five different monitors, some different PSUs (all of them 5volts, 3Amps), and with various HDMI cables, but the issue persists.
Here’s what I’ve verified so far:
The CM4 boots the OS successfully, and I can access it via OpenSSH and Windows PowerShell.
The CM4 can reproduce video internally, I've tested through a Windows app (B.Beat Manager), and I can watch video on the app. That is, video playback works within the app’s interface, so GPU and system resources appear functional.
The problem appears specifically with video output through HDMI. The connected monitor is detected (/sys/class/drm/card0-HDMI-A-1/status shows connected), and EDID is readable.
I’ve tested several configuration options in config.txt without success:
hdmi_group=1
hdmi_mode=16 # 1080p60
hdmi_enable_4kp60=1
gpu_mem=256
dtoverlay=vc4-kms-v3d
Commands tried and results:
lsmod | grep vc4 → confirms vc4-drm and associated DRM modules are loaded.
cat /sys/class/drm/card0-HDMI-A-1/modes → lists all available modes.
modetest -M vc4 → shows connector HDMI-A-1 as connected, but attempting sudo modetest -M vc4 -s 33:8 fails with failed to find mode.
sudo fbset -xres 1920 -yres 1080 -depth 24 → fails with ioctl FBIOPUT_VSCREENINFO: Invalid argument.
sudo edid-decode /sys/class/drm/card0-HDMI-A-1/edid → reads monitor EDID correctly, including 1080p60 and 4K modes.
dmesg | grep -i drm → confirms vc4-drm initialized correctly and framebuffer device vc4drmfb exists.
Observations:
The internal video playback working suggests the GPU and OS are functional.
HDMI output appears to fail during mode setting / buffer initialization (as seen with modetest and fbset).
The issue is not cable or monitor-specific.
I’m looking for guidance on:
How to get HDMI output working reliably with the CM4 on KMS/VC4 DRM.
Whether additional config.txt tweaks or overlays are required for 1080p/4K output.
Any known limitations with specific I/O boards or HDMI monitors.
Thanks in advance for any advice or guidance!
Statistics: Posted by TFS — Tue Sep 09, 2025 3:28 am