2021–06–14: Hints on debugging HDMI output on Pinephone

Some people have issues using external monitor with pinephone.

There are some ways to debug it. The most reliable one is to check the state of DRI in debugfs.

If you expect output on the monitor and there's none, you can check contents of file /sys/kernel/debug/dri/0/state or /sys/kernel/debug/dri/1/state to see what it says about the current state of the display pipeline as configured by your compositor. With only internal display turned on it will contain:

...

crtc[45]: crtc-0
        enable=1
        active=1
        self_refresh_active=0
        planes_changed=1
        mode_changed=0
        active_changed=0
        connectors_changed=0
        color_mgmt_changed=0
        plane_mask=2
        connector_mask=1
        encoder_mask=1
        mode: "720x1440": 60 72000 720 750 778 808 1440 1458 1468 1485 0x48 0xa
crtc[54]: crtc-1
        enable=0
        active=0
        self_refresh_active=0
        planes_changed=0
        mode_changed=0
        active_changed=0
        connectors_changed=0
        color_mgmt_changed=0
        plane_mask=0
        connector_mask=0
        encoder_mask=0
        mode: "": 0 0 0 0 0 0 0 0 0 0 0x0 0x0
connector[56]: DSI-1
        crtc=crtc-0
        self_refresh_aware=0
connector[58]: HDMI-A-1
        crtc=(null)
        self_refresh_aware=0

If you have in your dmesg:

...
DP state changed to 0x03
...

as the last DP state changed message, you should be able to just see your monitor's modes and enable the HDMI output via xrandr if you're using Xorg, or equivalent tool if you use something else.

It's the role of the compositor to enable the output to HDMI, so if you see connector[58]: HDMI-A-1 crtc=(null) and not connector[58]: HDMI-A-1 crtc=crtc-1 and some reasonable mode configured on crtc-1 it means that your compositor simply did not enable the HDMI output, so your monitor stays off.

If this happens on Xorg, xrandr --auto is the quickest way to at least get some output.

You need to consult documentation for your distribution's compositor to see how you can configure display output.

If /sys/kernel/debug/dri/*/state configuration looks correct, but your monitor is still not on, it's either a kernel or perhaps a HW issue.

If you sometime get to DP state changed to 0x03 after plugging in the dock, and sometimes not, you should check if you see some received SRC_CAP messages or received SVID or DP_ALT_ENTER messages in your dmesg after the last cable plugin event. If not, it means communication with the dock over the CC pins doesn't work or didn't happen for whatever reason, and the phone was not thus able to configure DP-Alt mode in the dock.

It may be due to some connector issue. Pinephone Type-C connector is a bit too much recessed into the body of the phone, and some Type-C cables don't plug in completely.