Display - Qualcomm Dragonwing Documentation

The IQ-8275 platform features a Qualcomm Adreno Display Processing Unit (DPU) providing hardware-accelerated image processing. The IQ8-EVK supports two simultaneous displays via dual DisplayPort outputs.

Display Capabilities

Interface	Capability
DP0	3840 × 2160 at 60 fps, 30 bpp
DP1	3840 × 2160 at 60 fps, 30 bpp
Concurrent	DP0 as primary + DP1 as secondary, both at 3840 × 2160 @ 60 fps

Supported features:

Wayland and Weston with upstream protocol
Weston compositor with DRM backend
2× DisplayPort with SST and MST support

Architecture

DPU Hardware

Component	Function
Bus Interface	Fetches data from memory
Source Surface Processing	Reads RGB/YUV surfaces; performs format conversion
Blending	Blends and mixes source surfaces
Destination Surface Processing	Converts and adjusts data for panel characteristics
Compression	Reduces bandwidth by sending compressed display buffers
Display Interface	Generates timings for connected display peripherals

Software Stack

Component	Description
Wayland Sink	Plug-in communicating with Weston to render the display
Weston	Wayland compositor; handles composition and rendering
DRM Backend	Manages Adreno DPU hardware resources and composition strategy
libdrm	Library providing DRM IOCTL APIs
Adreno DPU Driver	Manages all pixel data paths to panel interfaces

Setup

Connect primary display

Connect a DisplayPort cable to the eDP0 connector.

Connect secondary display (optional)

For dual display, connect a second DisplayPort cable to eDP1.

Power on

Power on the device. Weston launches automatically during boot and displays the flower pattern.

SSH Access

Default credentials: Username: ubuntu / Password: ubuntu

Testing and Verification

Run Weston EGL Client

weston-simple-egl

Expected output: A rotating triangle on the display at 60 fps. Press Ctrl+C to terminate.

GStreamer Video Playback

# H.264 playback
gst-launch-1.0 -v filesrc location=/etc/media/video.mp4 ! qtdemux ! queue ! \
  h264parse ! v4l2h264dec capture-io-mode=4 output-io-mode=4 ! \
  video/x-raw,format=NV12 ! waylandsink

# H.265/HEVC playback
gst-launch-1.0 -v filesrc location=/etc/media/video_hevc.mp4 ! qtdemux ! queue ! \
  h265parse ! v4l2h265dec capture-io-mode=4 output-io-mode=4 ! \
  video/x-raw,format=NV12 ! waylandsink

Debugging

sudo cat /sys/class/drm/card0-DP-1/status   # eDP0 cable status
sudo cat /sys/class/drm/card0-DP-2/status   # eDP1 cable status
sudo cat /sys/class/drm/card0-DP-1/modes    # Available EDID modes
dmesg | grep -i "dp\|display\|drm"

Troubleshooting

No Display Output (Black Screen)

cat /sys/class/drm/card0-DP-1/status
sudo dmesg | grep -i "dp\|display\|drm"

Verify cable connection to eDP0 or eDP1
Check display power and input source selection

Weston Fails to Start

journalctl -u weston
ls -l /dev/dri/card0
weston --idle-time=0 --continue-without-input --log=/home/ubuntu/weston.log

Dual Display Not Working

cat /sys/class/drm/card0-DP-1/status
cat /sys/class/drm/card0-DP-2/status
cat /sys/kernel/debug/dri/0/state

Weston Needs Restart

killall weston
sudo systemctl start weston-autostart
export XDG_RUNTIME_DIR=/run/user/$(id -u ubuntu)
export WAYLAND_DISPLAY=wayland-1

Resources

Resource	URL
DRM Internals	https://www.kernel.org/doc/html/v5.4/gpu/drm-internals.html
Wayland Protocol	https://wayland.freedesktop.org/
Weston Compositor	https://gitlab.freedesktop.org/wayland/weston
GStreamer Documentation	https://gstreamer.freedesktop.org/documentation/

​Display Capabilities

​Architecture

​DPU Hardware

​Software Stack

​Setup

​SSH Access

​Testing and Verification

​Run Weston EGL Client

​GStreamer Video Playback

​Debugging

​Troubleshooting

​Resources