IQ-615 - Qualcomm Dragonwing Documentation

Debug the high-definition multimedia interface (HDMI) display

Set switch SW7 to OFF as described in IQ-615 HDMI setup, then use the connector map and checks below.

Connect to the target through SSH and run target commands from the root shell. For instructions, see Sign in using SSH.

The HDMI output routes DSI0 through the ADV7511 DSI-to-HDMI bridge to HDMI-A-1.

Figure: IQ-615 HDMI connection

1. Identify the connector

Run the following command:

modetest -M msm -c

This lists the HDMI connector, its DRM ID, and its connection state.

Reference output

34      0       disconnected    HDMI-A-1        0x0             0       33

2. Check connector status and modes

Run the following command:

cat /sys/class/drm/card0-HDMI-A-1/status

This reports whether HDMI is connected. The expected result is connected.Run the following command:

cat /sys/class/drm/card0-HDMI-A-1/modes

This lists the modes reported by the connected monitor.If HDMI is disconnected or reports no modes, check the cable, monitor power, and selected HDMI input. DRM object IDs and card numbers can vary by build.

3. Check the active DRM state

If debugfs is not mounted, run the following command:

mount -t debugfs none /sys/kernel/debug

This makes DRM state and interface debug data available.Run the following command:

modetest -M msm -c -p

This shows the HDMI encoder, CRTC, mode, and plane.

Reference output

Encoders:
id      crtc    type
33      0       DSI

Run the following command:

cat /sys/kernel/debug/dri/0/state

This shows the kernel DRM connector, encoder, CRTC, and plane state.For HDMI-A-1, confirm one active display pipeline:

status: connected
A nonzero CRTC ID
active=yes for that CRTC
A plane whose crtc field matches that CRTC ID

Restore Weston after testing a display mode.To test a different mode, follow Run DRM modetest, then Relaunch Weston before returning to Weston tests.

4. Check interface signals

Run the following command:

cat /sys/kernel/debug/clk/disp_cc_mdss_pclk*/clk_rate

This prints the available DSI pixel-clock rates used by the HDMI bridge in Hz.Compare the rate with the active CRTC pixel clock, which modetest reports in kHz. If the clock path is absent, continue with the DRM state and kernel log checks.

5. Check current-boot kernel messages and live display events

Run the following command:

journalctl -k -b --no-pager -o short-monotonic | grep -Ei 'adv7511|adv7533|adv7535|hdmi|edid|dsi|dpu|drm'

This shows bridge, EDID, DSI, and DRM messages from the current boot only. If it returns no lines, capture live data while reproducing the issue.

Reference output

[   12.060926] adv7511 0-003d: supply v1p2 not found, using dummy regulator
[   12.326611] msm_dpu ae01000.display-controller: bound ae94000.dsi
[   12.512759] [drm] Initialized msm 1.13.0 for ae01000.display-controller

To capture display events while reproducing the issue, run the following command:

journalctl -f

This follows new Weston and kernel messages. Run it without -k so the output includes compositor connector changes and output enablement. Reproduce the issue, then press Ctrl+C.Look for connector-state changes, EDID or mode detection, output enablement, and driver errors. Compare the relevant messages with the connector status and active DRM state.EDID or I2C errors point to the monitor, cable, or bridge.

6. Interpret the result

Result	Likely area	Next action
`disconnected` after reconnecting, or no new display message and no status change	Cable, monitor input, bridge, or HPD path	Reseat the cable, select the HDMI input, and recheck connector status.
Connected with no modes or EDID/I2C errors	Monitor, cable, or bridge	Check the cable and monitor, then inspect bridge messages.
Mode reported, but the connector, CRTC, and plane do not form one active pipeline	DRM or compositor	Check the active DRM state and Weston status.
Active CRTC but blank screen	Bridge or Weston	Compare the DSI clock, bridge log, and Wayland output.

Verify the Weston service before checking the output layout.Run the following command:

systemctl is-active weston

The expected result is active. If the service is not active, Relaunch Weston before continuing.

7. Check Weston and the output layout

Run the following command:

journalctl -b -u weston -n 40 --no-pager

This shows the latest Weston messages from the current boot.Run the following command if Weston is active but the display is blank:

find /run/user/<weston-uid> -maxdepth 1 -type s -name 'wayland-*' -printf '%f\n'

This lists the available Wayland socket names.Run the following command after replacing the placeholders:

runuser -u weston -- env XDG_RUNTIME_DIR=/run/user/<weston-uid> WAYLAND_DISPLAY=<socket-name> wayland-info

Compare the Weston output with DRM state.This prints Weston output information. Find the selected display output and compare it with the DRM connector and CRTC state. If Weston is inactive, Relaunch Weston before continuing.

​Debug the high-definition multimedia interface (HDMI) display

​1. Identify the connector

​2. Check connector status and modes

​3. Check the active DRM state

​4. Check interface signals

​5. Check current-boot kernel messages and live display events

​6. Interpret the result

​7. Check Weston and the output layout

Debug the high-definition multimedia interface (HDMI) display

1. Identify the connector

2. Check connector status and modes

3. Check the active DRM state

4. Check interface signals

5. Check current-boot kernel messages and live display events

6. Interpret the result

7. Check Weston and the output layout