My laptop runs on Debian 9 and I try to have a dual monitor.
My first monitor use the VGA ports and works well but the second use the HDMI port and displays nothing.
However, the monitor is detected by my debian like you can see below:
You can see what is my processor Graphics Controller below:
lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
You can see below the output of the command
HDMI-1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 531mm x 299mm 1920x1080 60.00*+ 59.94 1600x1200 60.00 1680x1050 59.88 1280x1024 75.02 60.02 1440x900 59.90 1280x960 60.00 1152x864 75.00 1280x720 60.00 59.94 1024x768 75.03 70.07 60.00 832x624 74.55 800x600 72.19 75.00 60.32 56.25 720x480 60.00 59.94 640x480 75.00 72.81 66.67 60.00 59.94 720x400 70.08 DP-1 disconnected (normal left inverted right x axis y axis)