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How to get a HDMI-conection to life, without rebooting

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fred44nl
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How to get a HDMI-conection to life, without rebooting

#1 Post by fred44nl »

when Linux boots, in my case Debian 9, it finds the available hardware and loads firmware/software accordingly.
my machine is connected with HDMI to my TV.
when this TV is off, or using another HDMI connection, Linux sees the connection as dead.
so, nothing is loaded.
when later the HDMI channel for the Linux machine is selected, it simply is not working.

how can I get this connection working, without rebooting ??
could I use modprobe or something similar ??
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Re: How to get a HDMI-conection to life, without rebooting

#2 Post by bw123 »

...
my machine is connected with HDMI to my TV. when this TV is off, or using another HDMI connection, Linux sees the connection as dead. so, nothing is loaded.
...
I'm confused by your description. It's better if you show us with output from the OS. What do you mean by "Linux sees the connection as dead?"

You seem to be saying that firmware is not loaded when the TV display is turned off, but is loaded when the TV is on? Show us. Paste something from the OS that says what firmware you are talking about.

The go-to app for display trouble is xrandr, pretty easy to find some help with a simple search on the forum here or the internet. Sometimes it's as easy as running xrandr with --auto to fire up a disabled output.

If you want to help people help you, it might be a good idea to install pkg inxi and show people the info it provides about your system.

p.s. don;t run a bunch of commands you find on the internet without understanding them. modprobe is probably okay, but there are many other commands that can really mess things up. Be careful with sudo or when running things as root.
Last edited by bw123 on 2018-09-16 13:12, edited 1 time in total.
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CwF
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Re: How to get a HDMI-conection to life, without rebooting

#3 Post by CwF »

Simple solution is to boot with everything on. Not sure how much of this issue is DE related, but if all is on my 4 head hypervisor boots into my preferred config. The basic XFCE settings panel "Display" does fine. Moving sound to and from hdmi for me requires a change in the PulseAudio plugin, again in XFCE. I don't often, but I can switch up the displays live. Enabling and Disabling are not the same number of clicks, but it works.

So boot with everything on and from there it may be up to the DE.

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fred44nl
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Re: How to get a HDMI-conection to life, without rebooting

#4 Post by fred44nl »

sorry for the limited info.
my machine runs basically headless and is used for streaming video over DLNA.
but when the TV cannot handle the video specs., I have to use HDMI output to the TV.
apart from ssh, I use RealVNC to manage the system.
the desktop on my machine is LXDE.

when I turn on the TV, select the correct HDMI-port and reboot the system, I get the rdp0: screen on the TV.
doing the same, when the TV is off, and selecting the correct HDMI-port later, there is a blank screen, with nothing on. this is not the screen-saver.
don't know how to make this visible for you :)

when I make an ssh-connection and run xrandr --auto, it says "Can't open display"
I did run inxi:
fred44nl@Debian:~$ inxi -b
System: Host: Debian Kernel: 4.9.0-8-amd64 x86_64 (64 bit) Console: tty 0
Distro: Debian GNU/Linux 9 (stretch)
Machine: Device: desktop Mobo: Compulab model: fitlet2 v: 1.1
UEFI: American Megatrends v: FLT2.MBM2.0.40.01.00 date: 07/05/2018
CPU: Quad core Intel Celeron J3455 (-MCP-) speed/max: 799/2300 MHz
Graphics: Card: Intel Device 5a85
Display Server: X.org 1.19.2 drivers: modesetting (unloaded: fbdev,vesa)
tty size: 132x36 Advanced Data: N/A out of X
Network: Card-1: Intel Wireless 8260 driver: iwlwifi
Card-2: Intel I211 Gigabit Network Connection driver: igb
Card-3: Intel I211 Gigabit Network Connection driver: igb
Drives: HDD Total Size: 1063.6GB (50.7% used)
Info: Processes: 213 Uptime: 3:32 Memory: 1241.0/3778.2MB Init: systemd runlevel: 5
Client: Shell (bash) inxi: 2.3.5
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Re: How to get a HDMI-conection to life, without rebooting

#5 Post by CwF »

Gotchya.
So my advice doesn't apply! You need it off, then load live.
Thinking....

Targenor
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Re: How to get a HDMI-conection to life, without rebooting

#6 Post by Targenor »

fred44nl wrote:when Linux boots, in my case Debian 9, it finds the available hardware and loads firmware/software accordingly.
my machine is connected with HDMI to my TV.
when this TV is off, or using another HDMI connection, Linux sees the connection as dead.
so, nothing is loaded.
when later the HDMI channel for the Linux machine is selected, it simply is not working.

how can I get this connection working, without rebooting ??
could I use modprobe or something similar ??

Do you know if linux enter sleepmode?

Try this:
nano /etc/lightdm/lightdm.conf
[SeatDefaults]
xserver-command=X -s 0 -dpm
It should prevent linux from entering sleepmode, keeping the connection alive.

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debiman
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Re: How to get a HDMI-conection to life, without rebooting

#7 Post by debiman »

fred44nl wrote:apart from ssh, I use RealVNC to manage the system.
the desktop on my machine is LXDE.

(...)

when I make an ssh-connection and run xrandr --auto, it says "Can't open display"
ooookaaaayyy....
so, (speaking very slowly & clearly) - have - you - tried - doing - the - same - with - the - VNC - connection -- ???
(same for the inxi output btw)

PS:
generally speaking, you have been posting similar qquestions about your headless multimedia setup for quite a while now.
have you considered that you might be doing yourself & everyone else a big favour if you do some serious reading of documentation?
a lot of it is probably already on your system, but usually the www is easier to search.

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fred44nl
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Re: How to get a HDMI-conection to life, without rebooting

#8 Post by fred44nl »

Targenor wrote:Do you know if linux enter sleepmode?
the device is definitively not in sleep mode, as I can reach it with ssh all the time
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fred44nl
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Re: How to get a HDMI-conection to life, without rebooting

#9 Post by fred44nl »

debiman wrote: so, (speaking very slowly & clearly) - have - you - tried - doing - the - same - with - the - VNC - connection -- ???
I am working on VNC now.
(same for the inxi output btw)
my inxi output is in a previous post.
may be you overlooked it :)

P.S.:
apparently you are missing the fact that I am a newcomer.
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debiman
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Re: How to get a HDMI-conection to life, without rebooting

#10 Post by debiman »

fred44nl wrote:P.S.:
apparently you are missing the fact that I am a newcomer.
all the more reason to read some documentation.

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