Everything works with the rpi3. Why not with the rpi4?

    Hello! I have been using LibreELEC with a Raspberry Pi 3 for several years without any issues. Recently, I decided to set up a second LibreELEC system for another TV in my home. The plan was to buy a new Raspberry Pi 4 to replace the current Pi 3 in my living room and use the Pi 3 with the second TV in a different location.

    However, I encountered a problem when trying to get a picture with the Raspberry Pi 4 connected in place of the Pi 3, which was previously connected to my Denon amplifier and Samsung TV. Since it works with the Pi 3, I know that the HDMI cables, amplifier, and TV are functioning correctly.

    I tried connecting the Raspberry Pi 4 directly to the TV, and it works fine that way. The issue seems to occur only when it is connected through the Denon amplifier.

    I have tried various different settings in the config.txt file, but none of them have worked. One of the settings I attempted to use is:

    Code
    hdmi_safe_mode=1

    I also tried several other parameters in place of the above setting:

    Code
    hdmi_force_hotplug=1 
hdmi_group=1 
hdmi_mode=16

    I also tried to use hmdi boost (with 7 or 8) but nothing works.

    And also ignore the edid.

    No luck at all.

    In your opinion, if everything worked well with the raspberry pi 3, there must be a solution with the raspberry 4, right?


    Thank you very much.

    Is the Pi3 running the same version of LE as the Pi4?

    It is more likely a change in behaviour due to different versions.

    All the "hdmi_" settings you've mentioned apply to the deprecated firmware display driver.

    LE10/11/12 use the kms driver (kernel side) rather than fkms (firmware side) used by LE9.

    The kms driver does rely on a fully working hdmi cable (i.e. reporting hotplug and edid correctly).

    The fkms driver was more likely to somewhat work with a faulty cable.

    As a simple test, connect the Pi4 to the display without an sdcard inserted.

    It should show a diagnostic screen, that includes info about hotplug (HPD) and edid.

    What does it show?

    I didn't know that in the new version of LE, there is a new KMS driver, which explains why changing hdmi_param didn't make any difference.

    I forgot to mention that my receiver is not 4K. I just want to be able to have 1080p for now.

    So I booted my Pi without an SD card and this time, I saw the boot screen.

    The display line is:

    Quote

    Display: DISPO0: HDMI HPD=1 EDID=OK #2 DISP1: HDP=0 EDID=none #0


    Also, yesterday I was able to decode the EDID of my receiver via SSH, so I think the HDMI cable is working correctly.

    Is there a way to force the Pi to boot in 1080p with the DKMS driver?


    Thank you very much for your time!

    I find some information on the forum to start by myself.

    So here's my last test. I put this in my config.txt file:

    Code
    dtoverlay=vc4-fkms-v3d,cma-515


hdmi_ignore_edid=0xa5000080
hdmi_ignore_cec_init=1
hdmi_force_hotplug=1
hdmi_group=1
hdmi_mode=16
#config_hdmi_boost=7
#hdmi_drive=2

    but still no luck
    (i've tried without ignore_edit, with config_hdmi_boost, and hdmi_drive=2 also)

    HDMI options at config.txt are outdated since LE 10+. Edit cmdline.txt instead, and append this to the end of the line:

    Code
    video=HDMI-A-1:1920x1080@60D