Hello, I don't know where I can/should write this question... Please refer if I should write any post/bug/question somewhere... The problem I have : Last days I try to connect my laptop Dell XPS L502x with monitor Iiyama Prolite E1900S through DVI-D input. Dell XPS L502x has Optimus graphics card (intel/nvidia). I try to use integrated Intel card which is physically related with miniDP output. I use LogiLink miniDP/HDMI adapter (CV0045A). I don't know what means error : [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID:  (err -6) I did a few tests. First, I have connected Panasonic TV to the same adapter and TV was discovered correctly. So I thought that the problem can be EDID that my laptop can't read via miniDP/HDMI adapter from IIyama monitor. I have read EDID from this monitor when I connected to another computer. I saved EDID of Panasonic TV, too. Next (see case 02 below) after few days I found a way to store EDID into initramfs. I played with kernel parameters (drm.edid_firmware=... , video=... ) on connection with Panasonic TV just to be sure, that Dell is using EDID builded-in initram. Display of Panasonic TV seems to work according to those parameters. Finally, I have connected IIama PLE 1900S monitor, but display was off. When X server has started, I checked xrandr -q command which gave me all resolutions/refresh rates allowed exactly for this monitor. So EDID has been read. I have checked values : cat /sys/class/drm/card1-HDMI-A-1/ enabled cat /sys/class/drm/card1-HDMI-A-1/ connected cat /sys/class/drm/card1-HDMI-A-1/ 1280x1024 1280x1024 1280x960 1152x864 1024x768 1024x768 1024x768 832x624 800x600 800x600 800x600 800x600 640x480 640x480 640x480 640x480 720x400 Everything (only in my opinion!) seems to be fine, but display is not active. The only difference which I have observed is : [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID: DP-HDMI ADAPTOR\004 (err 0) and [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID:  (err -6) When I get error -6, than display is not activated... What does it mean ??? What can I do with it ? Below I put more details about my tests. In all cases /etc/X11/xorg.conf and /etc/X11/xorg.conf.d/* were empty(not used). Recently I have removed package ubuntu-drivers (as I remember) which contains "gpu-manager". I leave X server configuration for this moment. I saw that if I had no error (DP dual mode HDMI ID) than display was active even before X server starts. So in my opinion I can leave it now... The complete logs are in attachment. Best regards. ============================== [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID:  (err -6) case 01 - connected TV Panasonic to HDMI input via miniDP/HDMI adapter from miniDP port of laptop Dell-XPS-L502X, no extra kernel parameters cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-4.15. root=UUID=95f70d80-0833-47f2-a ro debug drm.debug=0xe Apr 03 18:09:21 Dell-XPS-L502X kernel: [drm:intel_hdmi_detect [i915]] [CONNECTOR:58:HDMI-A-1] Apr 03 18:09:21 Dell-XPS-L502X kernel: [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID: DP-HDMI ADAPTOR\004 (err 0) Apr 03 18:09:21 Dell-XPS-L502X kernel: [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode adaptor ID: a0 (err 0) Apr 03 18:09:21 Dell-XPS-L502X kernel: [drm:intel_hdmi_set_edid [i915]] DP dual mode adaptor (type 2 HDMI) detected (max TMDS clock: 300000 kHz) Apr 03 18:09:21 Dell-XPS-L502X kernel: [drm:drm_detect_monitor_audio [drm]] Monitor has basic audio support Apr 03 18:09:21 Dell-XPS-L502X kernel: [drm:drm_helper_hpd_irq_event [drm_kms_helper]] [CONNECTOR:58:HDMI-A-1] status updated from unknown to connected ============================== case 02 - connected TV Panasonic to HDMI input via miniDP/HDMI adapter from miniDP port of laptop Dell-XPS-L502X, see below extra kernel parameters cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-4.15. root=UUID=95f70d80-0833-47f2-a ro debug drm.debug=0xe video=HDMI-A-1:1280x720-16@50D drm.edid_firmware=HDMI-A-1:edi Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_hdmi_init_connector [i915]] Adding HDMI connector on port C Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm] forcing HDMI-A-1 connector on Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_connector_init [drm]] cmdline mode for connector HDMI-A-1 1280x720@50Hz Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_hdmi_init_connector [i915]] Using DDC pin 0x4 for port C (platform default) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_dp_init_connector [i915]] Adding DP connector on port C Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_dp_init_connector [i915]] using AUX C for port C (platform default) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_hdmi_detect [i915]] [CONNECTOR:58:HDMI-A-1] Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm] Got external EDID base block and 1 extension from "edid/tv.bin" for connector "HDMI-A-1" Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID: DP-HDMI ADAPTOR\004 (err 0) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode adaptor ID: a0 (err 0) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_hdmi_set_edid [i915]] DP dual mode adaptor (type 2 HDMI) detected (max TMDS clock: 300000 kHz) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_detect_monitor_audio [drm]] Monitor has basic audio support Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_helper_hpd_irq_event [drm_kms_helper]] [CONNECTOR:58:HDMI-A-1] status updated from unknown to connected Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_helper_probe_single_c [drm_kms_helper]] [CONNECTOR:58:HDMI-A-1] Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_hdmi_force [i915]] [CONNECTOR:58:HDMI-A-1] Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm] Got external EDID base block and 1 extension from "edid/tv.bin" for connector "HDMI-A-1" Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID: DP-HDMI ADAPTOR\004 (err 0) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode adaptor ID: a0 (err 0) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:intel_hdmi_set_edid [i915]] DP dual mode adaptor (type 2 HDMI) detected (max TMDS clock: 300000 kHz) Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_detect_monitor_audio [drm]] Monitor has basic audio support Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_add_display_info [drm]] non_desktop set to 0 Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_add_display_info [drm]] HDMI: DVI dual 0, max TMDS clock 190000 kHz Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_add_display_info [drm]] non_desktop set to 0 Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_add_display_info [drm]] HDMI: DVI dual 0, max TMDS clock 190000 kHz Apr 03 18:48:07 Dell-XPS-L502X kernel: [drm:drm_edid_to_eld [drm]] ELD monitor Panasonic-TV ============================== case 03 - connected Monitor iiama ProLite E1900S to DVI input via miniDP/HDMI adapter + HDMI/DVI cable from miniDP port of laptop Dell-XPS-L502X, see below extra kernel parameters cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-4.15. root=UUID=95f70d80-0833-47f2-a ro debug drm.debug=0xe video=HDMI-A-1:1280x1024-16@75 drm.edid_firmware=HDMI-A-1:edi Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm] forcing HDMI-A-1 connector on Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:drm_connector_init [drm]] cmdline mode for connector HDMI-A-1 1280x1024@75Hz Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:intel_hdmi_init_connector [i915]] Using DDC pin 0x4 for port C (platform default) Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:intel_dp_init_connector [i915]] Adding DP connector on port C Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:intel_dp_init_connector [i915]] using AUX C for port C (platform default) Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:intel_hdmi_detect [i915]] [CONNECTOR:58:HDMI-A-1] Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm] Got external EDID base block and 0 extensions from "edid/monitor.bin" for connector "HDMI-A-1" Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:gmbus_xfer [i915]] GMBUS [i915 gmbus dpc] NAK for addr: 0040 w(1) Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:gmbus_xfer [i915]] GMBUS [i915 gmbus dpc] NAK on first message, retry Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:gmbus_xfer [i915]] GMBUS [i915 gmbus dpc] NAK for addr: 0040 w(1) Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:drm_dp_dual_mode_detect [drm_kms_helper]] DP dual mode HDMI ID:  (err -6) Apr 03 19:47:48 Dell-XPS-L502X kernel: [drm:drm_helper_hpd_irq_event [drm_kms_helper]] [CONNECTOR:58:HDMI-A-1] status updated from unknown to connected