I have bought the HDMI 7" 800x480 Display with Touchscreen (https://www.adafruit.com/product/2407) from adafruit and I'm having a problem I can't seem to fix. I'm using it with a Raspberry Pi 4B, currently it's plugged into HDMI-0.
I set it up just like the documentary states, I put this code in /boot/config.txt:
Code: Select all
# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=1
# uncomment to force a specific HDMI mode (here we are forcing 800x480!)
hdmi_group=2
hdmi_mode=87
hdmi_cvt=800 480 60 6 0 0 0
hdmi_drive=1
max_usb_current=1
Using this code first didn't really change the resolution though, neither on nor after boot, so I searched the web for more clues. I found some reddit-posts stating that using the fkms-driver instead of the kms seemed to help, so I changed this as well. Furthermore, I edited /boot/cmdline.txt to force a specific resolution by adding video=800x480M@60D, while simultaneously commenting the hdmi_group/mode/cvt/drive-lines out again.
With these settings, the Screen at least had the right resolution AFTER boot.
On boot, I get weird colored vertical stripes on the right side of the monitor, like it's using a different resolution on startup. AFTER the boot, it works just fine though. I figured that this isn't normal behaviour and at this point I'm glad it works after all, but the glitchy look on startup still rubs me the wrong way - So here I am, asking for help or pushes in the right direction. If you need more info, please tell me what I should paste here, I'm really out of ideas.
I add a photo I found on some reddit-posts that has the exact same appearance as my screen does. Using any other monitor or TV works fine with the pi, so I guess it's due to a problem with the unusual/"non-standard" resolution of 800x480. I also tried the other HDMI-Port, used different hdmi-cables and adapters, powered the monitor externally (which changed the weird vertical stripes to a black area, but still the resolution was wrong on boot) and the problem still remains - Which only leaves me with the idea that it's a software/driver-problem I can't figure out.
To clarify, what I mean with "on boot": The splashscreen and the "Press Shift for Recovery-Mode" are not in the right resolution, resulting in the big border on the right side. After that it seems to load the right one.
Edit:
I now set the monitor up like stated in the documentary again - so normal kms driver, hdmi_mode/group/drive/etc like in the doc. It works after boot and the right resolution is set, but still I get the splashscreen and "Press Shift for Recovery Mode"-Screen with the big black area on the right border.
I hope someone can help me out
Thanks in advance!