No HDMI signal -> "GMBUS EDID read failed, retry using GPIO bit-banging, skipping non-existent adapter i915 gmbus dpc"
Subject:
- HDMI port not working/no output
- mDP + Thunderbolt/USB-C are working/output
- Error message from dmesg log "GMBUS EDID read failed, retry using GPIO bit-banging"
System architecture:
- x86_64
- kernel: 5.11.0-gentoo
- Distribution: Gentoo
- see forum thread "HDMI not working" with help from NeddySeagoon here.
- graphics: Intel UHD 620
- Gnome Display manager + Sway (Wayland) compositor, see github issue I created there and
- dmidecode: https://dpaste.com/GSUQCFMAB
- Motherboard model: N150CU (TUXEDO)
- full list of hardware: https://linux-hardware.org/?probe=ad91e37e92
- Display Connectors:
- HDMI (no output)
- mDP (1920x1080 output)
- USB-C Thunderbolt (4k@60Hz output)
Log files:
- dmesg after cold boot with kernel command line "drm.debug=0x1e log_buf_len=1M"
1.) HDMI port connected to external monitor -> no signal \
https://paste.c-net.org/UncleanEnforced
Extract:
[ 1.833535] i915 0000:00:02.0: [drm:intel_hdmi_set_edid] HDMI GMBUS EDID read failed, retry using GPIO bit-banging
[ 1.833540] i915 0000:00:02.0: [drm:intel_gmbus_force_bit] enabling bit-banging on i915 gmbus dpc. force bit now 1
[ 1.841231] [drm:drm_do_probe_ddc_edid] drm: skipping non-existent adapter i915 gmbus dpc
2.) mDP connected to external monitor -> detected + signal
https://paste.c-net.org/BoneheadEduard
3.) USB-C/Display Port connected to external monitor -> detected + signal
https://paste.c-net.org/MemoirsKittens
4.) Kernel .config
https://dpaste.com/8434HE6DG
Extract:
CONFIG_I2C_GPIO=y
CONFIG_GPIOLIB=y
5.) Output of Sway Wayland compositor 'swaymsg -t get_outputs' when 3.) USB-C connection is established.
eDP-1 is the internal monitor (Laptop).
DP-1 is the USB-C running Display Port at 4k@60Hz.
https://dpaste.com/2YW588QDA
Output eDP-1 'Unknown 0x0747 0x00000000' (focused)
...
Output DP-1 'NEC Corporation EA271U 96101309NB'
...