Connecting second screen via HDMI

Question

I'm pretty new to Linux: I'm running under Ubuntu 14.04 Gnome which I recently installed (my laptop was OS-less when I bought it). It has an Intel Haswell Mobile chipset and I can't seem to connect a second screen (HP Pavillon 23xi) via HDMI.

Are there drivers that I should update or anything ?

Thank you to anyone for their help

Edit: Answer to Jan's comment :

~ sudo lsmod|grep 915    
i915                  783805  7 
drm_kms_helper         55071  1 i915
drm                   303102  6 i915,drm_kms_helper
i2c_algo_bit           13413  1 i915
video                  19476  1 i915

~ glxinfo |grep render isn't recognized

and

~ for i in /sys/class/drm/card*/enabled; do echo -en "$i\t"; cat $i;done
/sys/class/drm/card0-DP-1/enabled       disabled
/sys/class/drm/card0-eDP-1/enabled      enabled
/sys/class/drm/card0-HDMI-A-1/enabled   disabled
/sys/class/drm/card0-HDMI-A-2/enabled   disabled
/sys/class/drm/card0-VGA-1/enabled      disabled

Answer 1

I had exactly the same issue with my TV on second HDMI port of my Intel HD integrated graphics on Ubuntu 14.04 even 16.04.

Sometimes TV got detected, sometimes not. It was absolutely same under Windows where helped to disable graphic adapter in device manager for a while and re-enable it and TV on second HDMI got magically detected.

Finally I found a solution also for linux. Trouble is that HDMI port is not enabled and therefore TV/monitor not detected. Normally HDMI port should detect new hardware and enable itself automatically but unfortunately on my hardware this was not happening.

So solution is to enable HDMI port manually on boot. Eg. you have

/sys/class/drm/card0-HDMI-A-1/enabled   disabled
/sys/class/drm/card0-HDMI-A-2/enabled   disabled

So if you in grub during boot add these parameters to kernel

video=HDMI-A-1:e video=HDMI-A-2:e

It should according to http://distro.ibiblio.org/fatdog/web/faqs/boot-options.html enable both ports.

Afterwards just look which port is really used and edit /etc/default/grub with

GRUB_CMDLINE_LINUX_DEFAULT= ...keep options and add... video=HDMI-A...

Just run

update-grub

and it should works.

Eg. on my machine I have 3 HDMI ports but just 2 of them are connected on mainboard (one cannot be connected at all). If I enable all 3 connectors maximum resolution is 1024x768 so I needed to find out used two (in my case HDMI-A-2 and HDMI-A-3 where HDMI-A-3 was first one and HDMI-A-1 was disconnected from mainboard) and enable in grub only just these two, e.g. in my case boot line looks like this video=HDMI-A-2:e video=HDMI-A-3:e.

Currently I use Gigabyte Z87N-Wifi mainboard with one monitor on HDMI and TV on HDMI. With these settings TV get always detected after reboot.