How do you re-enable HDMI after Linux loses it?

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Petermint
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How do you re-enable HDMI after Linux loses it?

Post by Petermint » Wed Dec 05, 2018 3:03 am

I lost the HDMI port again. Both times are the same. I connected a TV to the HDMI output on my notebook to run VLC. Everything on the displays started breaking down with less and less working. I unplugged the TV and plugged a monitor back in to the HDMI port. HDMI no longer worked.

Last time I fixed it, there was a new release of LM available so I did a clean install. After performing a clean install, I found posts that told me to just edit some files in Linux. This time around, a dozen google searches have not found the posts.

The HDMI port must work because a monitor reacts to the port, showing connected or disconnected. The monitors work through VGA. Everything works except Linux does not recognise the port. This is the same as last time.

The first time I tried cycling through the monitor options using Ctrl-F5, the cycle brought up a flickering notebook display where HDMI should appear as the other screen. I had to reboot. After the reboot cycling through the monitor options with Ctrl F5 simply switches VGA on and off.

One post suggested deleting .monitors.xml but that was recreated exactly the same for default monitor and VGA but not HDMI.

There are no errors in syslog. There are only two startup lines with HDMI and both are exactly the same as when HDMI worked.

Petermint
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Re: How do you re-enable HDMI after Linux loses it?

Post by Petermint » Fri Dec 07, 2018 8:42 pm

HDMI is back. After no changes and about 10 reboots, HDMI works. Same computer. Same monitors. Same cables.

I searched for the posts mentioning the files that contain HDMI settings. Have not found them. Syslog still has only 2 lines mentioning HDMI and they are for audio, not video. Does anyone know to find the HDMI/VGA setup is in syslog?

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MrEen
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Re: How do you re-enable HDMI after Linux loses it?

Post by MrEen » Fri Dec 07, 2018 10:04 pm

Hi Petermint.

While I can't help with the issue you were having, I can offer one thing you can try if it happens again. Instead of rebooting, do a full shutdown and wait a minute or two before powering back up. Maybe before doing that, check your temps to see if heat might be an issue.

The only post I could find by you that was close to this issue was here, and judging by the lack of replies, I'm guessing you solved it yourself or found help outside this forum.

Petermint
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Re: How do you re-enable HDMI after Linux loses it?

Post by Petermint » Fri Dec 07, 2018 10:25 pm

do a full shutdown and wait a minute or two before powering back up
I shutdown the computer overnight and sometimes when travelling. The problem did not fix itself in the first few days but is gone now after several more reboots.
I'm guessing you solved it yourself or found help outside this forum.
The HDMI problem disappeared. I would like to find a solution for next time.

A previous multiple screen hibernation problem occurred in LM 18 and was avoided by unplugging the screens before closing the lid of the notebook. There were similar issues recorded in Ubuntu and higher up the development stream. Some of those issues where fixed in the Ubuntu used for LM 19. I tend to switch off the computer instead of using hibernation, which makes that problem less likely. I have not noticed the error in LM 19.

The HDMI fix I found some time ago included deleting lines from one of the system files.

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