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Author Topic: Pi 4 dual Monitor  (Read 10985 times)

Offline Rabie

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Pi 4 dual Monitor
« on: August 05, 2021, 12:21:51 AM »
Hello there,

i have installed piCore 13.x armv7l on pi 4 and i want to use 2 Monitors.

Anyway i have used on TinyCore pure64 xrandr for that

so i installed xrandr on piCore but i am getting the following:

Code: [Select]
$xrandr
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920x1080, maximum 1920x1080
default connected 1920x1080+0+0 0mm x 0mm
  1920x1080        0.00*

i already tried to add a new Mode like:
Code: [Select]
$cvt 1920 1080 60
# 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz
Modeline "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync

$xrandr --newmode "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
xrandr: Failed to get size of gamma for output default


How can i get this to work with xrandr ?

Thank you
« Last Edit: August 05, 2021, 12:44:26 AM by Rabie »

Offline Rabie

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Re: Pi 4 dual Monitor
« Reply #1 on: August 08, 2021, 04:21:44 AM »
Hi,

i found out that there is just one Framebuffer in PiCore:
Code: [Select]
$ls /dev/fb*
/dev/fb0

i don't know if this possible to make piCore work with 2 Monitors

Offline Juanito

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Re: Pi 4 dual Monitor
« Reply #2 on: August 08, 2021, 04:54:28 AM »
Have you tried using Xorg-3d and dtoverlay=vc4-kms-v3d-pi4?

Are both of the monitors hdmi?

Do you see both monitors mentioned in Xorg.0.log?

Offline Rabie

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Re: Pi 4 dual Monitor
« Reply #3 on: August 08, 2021, 07:04:37 AM »
Hi Juanito,
Quote
Have you tried using Xorg-3d and dtoverlay=vc4-kms-v3d-pi4?

i just tried that and the second Monitor stucks on the rainbow screen while booting.

Quote
Are both of the monitors hdmi?

the first one is direkt from HDMI to HDMI
the second is from HDMI to DVI (because my second Monitor doesn't has HDMI) But it work's when its the only Monitor connected

Quote
Do you see both monitors mentioned in Xorg.0.log?

i dont think so, it just says that the system use some Default Screen
Here ist the Log File (See Attachtment)


Offline Juanito

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Re: Pi 4 dual Monitor
« Reply #4 on: August 08, 2021, 08:31:25 AM »
I see a couple of problems:

* the expat2 extension does not seem to be loaded?
* the xf86-video-fbturbo extension prevents 3d acceleration from working

You could try deleting /usr/local/share/X11/xorg.conf.d/fbturbo.conf and re-starting X

Offline Rabie

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Re: Pi 4 dual Monitor
« Reply #5 on: August 08, 2021, 11:04:38 AM »
Hi Juanito,
Quote
* the expat2 extension does not seem to be loaded?
its already installed if this what you mean
Code: [Select]
$ tce-load -wi expat2
expat2 is already installed!

Quote
You could try deleting /usr/local/share/X11/xorg.conf.d/fbturbo.conf and re-starting X

nothing happens, the second Monitor still stuck on the rainbow screen

Offline Juanito

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Re: Pi 4 dual Monitor
« Reply #6 on: August 08, 2021, 11:13:58 AM »
Could you attach the latest Xorg.0.log

Offline Rabie

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Re: Pi 4 dual Monitor
« Reply #7 on: August 08, 2021, 11:28:31 AM »
Could you attach the latest Xorg.0.log
yes of course!

i hope, i am not doing it wrong
i did it like that:

Code: [Select]
sudo rm /usr/local/share/X11/xorg.conf.d/fbturbo.conf
startx

Offline Juanito

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Re: Pi 4 dual Monitor
« Reply #8 on: August 08, 2021, 12:17:22 PM »
The fbturbo driver is still being loaded, could you delete /usr/local/lib/xorg/modules/drivers/fbturbo_drv.so, exit the gui and re-start X

Offline Rabie

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Re: Pi 4 dual Monitor
« Reply #9 on: August 08, 2021, 01:34:39 PM »
The fbturbo driver is still being loaded, could you delete /usr/local/lib/xorg/modules/drivers/fbturbo_drv.so, exit the gui and re-start X

so i deleted the driver
Code: [Select]
sudo rm /usr/local/share/X11/xorg.conf.d/fbturbo.conf
sudo rm /usr/local/lib/xorg/modules/drivers/fbturbo_drv.so

i saw in the log that it loaded some lib:
/usr/local/lib/xorg/modules/libfbdevhw.so

so i deleted it too
Code: [Select]
sudo rm /usr/local/lib/xorg/modules/libfbdevhw.so

this is the new Log
do i have to kill some process bevor i start X again ?

Offline Juanito

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Re: Pi 4 dual Monitor
« Reply #10 on: August 09, 2021, 12:34:44 AM »
You should not delete /usr/local/lib/xorg/modules/libfbdevhw.so, this has nothing to do with the fbturbo driver.

Xorg is still using the fbturbo driver, which must mean that you have either not deleted it or are rebooting after having deleted it.

Do you see at least one of the screens blank when you load Xorg-3d (which loads graphics-KERNEL) and it enters kms mode?

Offline Rabie

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Re: Pi 4 dual Monitor
« Reply #11 on: August 09, 2021, 01:30:08 AM »
Hi Juanito,

Quote
Xorg is still using the fbturbo driver, which must mean that you have either not deleted it or are rebooting after having deleted it.
no i deleted both Files and did not reboot

i think i was doing the restart from X wrong :o

i deleted both Files:
Code: [Select]
sudo rm /usr/local/share/X11/xorg.conf.d/fbturbo.conf
sudo rm /usr/local/lib/xorg/modules/drivers/fbturbo_drv.so

and then i killed the x server:
Code: [Select]
sudo pkill -f "/usr/local/lib/xorg/Xorg -logfile /tmp/xorg.log -nolisten tcp"
and now when i do:
Code: [Select]
$sudo Xorg -configurethis what i get: (See Log)

and if i run:
Code: [Select]
$startxfailed in waitforX


Offline Juanito

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Re: Pi 4 dual Monitor
« Reply #12 on: August 09, 2021, 04:00:05 AM »
To exit to the console prompt you can use the exittc icon.

There is no need to use “Xorg -configure”, the automatic configuration should work.

First we need to check that you are in kms mode - if you reboot to the console prompt and then load Xorg-3d, do you see the screen blank and then come back again?

Does “dmesg | tail -20” show vc4 and v3d being initialised?
« Last Edit: August 09, 2021, 04:21:56 AM by Juanito »

Offline Rabie

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Re: Pi 4 dual Monitor
« Reply #13 on: August 09, 2021, 05:10:18 AM »
Quote
First we need to check that you are in kms mode - if you reboot to the console prompt and then load Xorg-3d, do you see the screen blank and then come back again?
i am sorry but I don't even know how do i enter the kms mode i just did like you said " with exittc => exit to prompt " is this the same as reboot to console prompt ?


Quote
First we need to check that you are in kms mode - if you reboot to the console prompt and then load Xorg-3d, do you see the screen blank and then come back again?
what do you mean with load Xorg-3d and the screen blanck ?

Quote
Does “dmesg | tail -20” show vc4 and v3d being initialised?


« Last Edit: August 09, 2021, 05:17:35 AM by Rabie »

Offline Juanito

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Re: Pi 4 dual Monitor
« Reply #14 on: August 09, 2021, 05:16:27 AM »
Reboot means power-off and power-on again.

Once you have rebooted to the console prompt, issue the command “tce-load -i Xorg-3d”. This will have the effect of loading the graphics-KERNEL module , which, if you entered the dtoverlay line mentioned previously into config.txt, will blank the screen briefly.