Display Problems

No Display Output

Complete Black Screen

1. Verify hardware connections

   • DSI cable seated correctly
   • Power cable connected to 5V and GND
   • No bent pins in connectors

2. Check boot activity

   • Green LED on Pi should flash during boot
   • If Pi doesn’t boot, issue is not display-related

3. Test with SSH

   ssh pi@raspberrypi.local
   # If this works, display config is the issue

4. Review config.txt

   sudo nano /boot/firmware/config.txt
   # Ensure these lines exist:
   # dtoverlay=vc4-kms-v3d
   # dtoverlay=vc4-kms-dsi-waveshare-panel-v2,8_0_inch_a

Display Goes Black After Boot

The display may work during boot splash but go black at login. This indicates:

1. X11/Wayland issue

   # Check Xorg log
   cat /var/log/Xorg.0.log | tail -50

2. Resolution mismatch

   # Force resolution in cmdline.txt
   video=DSI-1:800x1280e

3. Compositor conflict

   • Try disabling desktop effects
   • Switch from Wayland to X11 (or vice versa)

Image Quality Issues

Blurry Display

• Running at non-native resolution
• Scaling enabled in desktop settings

Fix: Ensure you’re running at native 800×1280.

Lines or Artifacts

Pattern	Cause
Horizontal lines	Cable connection issue
Vertical lines	Panel damage or driver issue
Random pixels	Memory/power issue
Repeating pattern	Wrong driver loaded

For cable issues:

1. Power off
2. Reseat DSI cable firmly
3. Check for cable damage
4. Power on

Color Problems

The IPS panel should display accurate colors. Issues indicate:

• Washed out: Check brightness isn’t at maximum
• Color cast: Panel defect (contact Waveshare)
• Inverted colors: Wrong driver (verify overlay name)

Backlight Issues

Screen is Very Dark

# Check current brightness
cat /sys/class/backlight/*/brightness

# Set to maximum
echo 255 | sudo tee /sys/class/backlight/*/brightness

Backlight Not Responding to Commands

1. Verify backlight sysfs exists:

   ls /sys/class/backlight/

2. Check permissions:

   ls -la /sys/class/backlight/*/brightness

3. Use sudo if needed:

   echo 200 | sudo tee /sys/class/backlight/*/brightness

Backlight Flickers

• Random flicker: Power supply issue (needs ≥0.8A)
• Regular flicker: PWM frequency conflict (rare)
• Flicker at low brightness: Normal for PWM dimming

Rotation Problems

Display Upside Down

# Add to cmdline.txt (at beginning of line)
video=DSI-1:800x1280e,rotate=180

Wrong Aspect Ratio

The display is portrait (800×1280). If showing as landscape:

1. The display may be rotated 90°
2. Check xrandr --query for current mode
3. Set correct rotation in Screen Configuration

Cannot Rotate

Note

When using HDMI and DSI together, both displays share rotation settings and cannot be rotated independently.

Detection Issues

Display Not Detected

# Check connected displays
ls /sys/class/drm/*/status

# Check DSI driver
lsmod | grep dsi

If no DSI output appears:

1. Overlay may not be loading
2. Check /boot/firmware/overlays/ for waveshare files
3. Try pre-built Waveshare image

Multiple Displays Confused

# Identify displays
xrandr --query

# Set primary display
xrandr --output DSI-1 --primary