Change xorg Framebuffer to fb1 to support recent Raspbian releases

[jupiterbjy]

EDIT: Refer This solution instead.

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For my 3.5" GPIO Display(MPI3501), changing framebuffer in xorg config from fb0 to fb1 fixed the issue.

If this wrong framebuffer actually is the only reason why (seemingly) all goodtft displays are displaying blank screen - I suggest to add a patch for it in all driver installation scripts.

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Following are steps I took to fix the blank (black) screen.
Tested on Raspberry Pi 1B+ / Raspberry Pi OS (32bit) - release 2023-02-21

1. Make sure driver is installed correctly
   Check if dtoverlay specified in bottom section of /boot/config.txt/ exists in /boot/overlays/.

   pi@raspberrypi:~/LCD-show/usr $ cat /boot/config.txt | grep ^dtoverlay
   dtoverlay=tft35a:rotate=90
   

   pi@raspberrypi:~/LCD-show/usr $ ls -l /boot/overlays/ | grep tft35a
   -rwxr-xr-x 1 root root   2616 Apr 28 03:07 tft35a.dtbo
   -rwxr-xr-x 1 root root   2616 Apr 28 03:45 tft35a-overlay.dtb
   

2. Open xorg config

   sudo vi /usr/share/X11/xorg.conf.d/99-fbturbo.conf
   

3. Change framebuffer from 0 to 1 & Save

   Option "fbdev" "/dev/fb0" 
   

   ↓↓↓

   Option "fbdev" "/dev/fb1"
   

4. try running x server on fb1 and see if it works:

   sudo FRAMEBUFFER=/dev/fb1 startx
   

5. Reboot and enjoy
   If it's stuck at white screen, pull out power and reconnect.
   It'll eventually show desktop after long black screen - stuck on wrong rotation though. Touch xy are reversed.

   

Above answers are combination of 5-yr-old RPi forum's post and OctoPrint Community's post. Took 2 weeks to find but worth enough.

[Kristian Kraljic]

@jupiterbjy any idea how to make this work with enabling the Full KMS OpenGL drivers in raspi-config? Seems if I enable Full KMS the 99-fbturbo.conf driver is no longer loaded / needed and I don't know how to switch to FB1... I need the full OpenGL drivers to load Midori, which will not work on the legacy drivers for some reason. Any idea? Appreciate any hint.

[jupiterbjy]

@kristian Ah sadly I do not know the other workaround either - I found two decade old methods during search, but I have low hope on these 2 methods.. sorry!

[3raz0r]

Big THX to your research for fixing this bug.
I was was really frustrated, the display (in my case a 2,8 inch 320 x 240 cheap ILI9341) worked not regulary on a raspi zero and raspi zero w, mostly he didnt.
An when he worked, the framerate was crap and a black screen showed off after a few minutes (it was not the screensaver). fixing the /usr/share/X11/xorg.conf.d/99-fbturbo.conf file did it for me. This should be fixed for the future. THX again

[jupiterbjy]

@3raz0r such simple fix never listed on document.. this is quite sad to see, so this is universal problem existing not just my MPI3501 but also ILI9341, thanks for confirmation - I guess now I'm pretty sure all waveshare/goodtft products are experiencing same. Glad it worked for you!