RPI 4 Monitor detection - No Signal

  • Hi


    I often take my LibreELEC with me to friends & vacations

    and I noted that on RPI4 the monitor detection is problematic comparing to RPI3, and often i get “No Signal”


    Can someone explain why when I use LibreELEC 10.0.2 on RPI 4

    on some monitors I’m getting “No Signal” and to fix it I need to edit the cmdline.txt

    But in RPI3 with LibreELEC 10.0.2 the detection of the monitor works fine


    Thanks Dan



  • Could be an HDMI cable issue. On 4K output devices, RPi4 fires a higher data rate, compared to RPi3. Some cables are unable to transmit such data rates, so the screen goes black. Always use an HDMI 2.0 or 2.1 cable with your RPi4.

  • I'm using the original cable of the RPI4,

    and this cable is working fine with some monitors like the one on my living room.

    But for some monitors (like on my friends monitor) I get the "no signal" :(

  • With working monitor connected, run getedid create command from SSH console and then try connecting with non-working monitors.

  • With working monitor connected, run getedid create command from SSH console and then try connecting with non-working monitors.

    As I'm in same situation whilst travelling I'm curious how to achieve this.

    Bring a computer to holidays? Run the getedid command at home before travelling?

    Or perhaps find the rootcause?


    The setup was working well with Rpi3/LE9.2 I'm curious why the setup is so unreliable as it is now.

  • It's hard to say but it looks the current HDMI detection procedure needs to be optimized a bit.

    So I would try to configure the LE to work with some fixed monitor settings, to boot properly and work even without monitor attached.

    One way could be through kernel boot parameters (look here: Force HDMI OUTPUT ), the second way (which helped me when I permanently lost HDMI audio on my old monitor after some recent LE 11 Nightly update) could perhaps be the EDID save from working configuration (working monitor attached) as outlined above. Hope this could help. Try to run getedid create at home before travelling and you'll see... If it does not help, you may remove it through getedid delete and then reboot LE.


    BTW. Maybe it could be useful for developers to have the edid files from not-working configurations to analyze.

    If i am not mistaken, the edid create saves the edid-HDMI-A-1.bin file to /storage/.config/firmware/edid/ folder (and also edid-HDMI-A-2.bin for devices with two HDMI ports like RPi 4B etc.).

    And it's possible to look what's there with:

    edid-decode /storage/.config/firmware/edid/edid-HDMI-A-1.bin

    Edited 3 times, last by ghtester ().

  • Try to run getedid create at home before travelling and you'll see... If it does not help, you may remove it through getedid delete and then reboot LE.

    Well, that sounds a bit like "hit or miss"...

    This might work is not so funny when away from home and Your Rpi shows... Nothing.

    And bringing a computer for this purpose only (removing getedid data) sounds just a bit, well, ridiculous.

  • I'm using the original cable of the RPI4,

    and this cable is working fine with some monitors like the one on my living room.

    But for some monitors (like on my friends monitor) I get the "no signal" :(

    Is the monitor / TV on your living room 4K?


    The reason is hard to tell without seeing a log file.

    For a non-working monitor it would help to get the kodi.log after the test.

    (if pastekodi (see below) doesn't work, you can also get it directly from microSD, and upload to PasteBin)


    You have to activate debug logging on a working monitor first.


    Please provide a full debug log.

    How to post a log (wiki)

    1. Enable debugging in Settings>System Settings>Logging
    2. Restart Kodi
    3. Replicate the problem.

    Full logs only. No modified logs.

    Do not post your logs directly into the forum,
    use Settings > LE Settings Addon > System > Paste system logs
    and post the link.
  • I enabled log on the working monitor (hd not 4K)

    Turned off.

    Then connected to a "problematic" monitor

    Power on.

    Got the No Signal

    Unplugged the RPI4 from the power supply.

    Reconnected to the working monitor and to the power

    And uploaded both the log and the crash log

    Log Http://ix.io/4bK9

    Crash log Http://ix.io/4bKa

  • I would try adding hdmi_force_hotplug=1 to /flash/config.txt file. And if it does not help, see the post #6.

  • You have banned repos / add-ons installed. We will not give you support until you've been uninstalled them.

  • I would try adding hdmi_force_hotplug=1 to /flash/config.txt file. And if it does not help, see the post #6.

    Thank you,
    This worked out for me :)
    at lease with the monitors that i have on hand

    Quote from Da Flex

    You have banned repos / add-ons installed. We will not give you support until you've been uninstalled them.

    You are obviously right,
    I didn't removed the repos /add-ons because it was obvious to me that it is a general issue and not related to any add-on

  • You are obviously right,
    I didn't removed the repos /add-ons because it was obvious to me that it is a general issue and not related to any add-on


    The Kodi and LibreElec forums have a policy of not supporting those who use banned repos/add-ons, due to the bad reputation that they have given Kodi (to the extent that some online auction sites now treat 'Kodi' as a banned word in listings).


    Doesn't matter whether the issue is related to them or not.

  • BTW. Maybe it could be useful for developers to have the edid files from not-working configurations to analyze.

    If i am not mistaken, the edid create saves the edid-HDMI-A-1.bin file to /storage/.config/firmware/edid/ folder (and also edid-HDMI-A-2.bin for devices with two HDMI ports like RPi 4B etc.).

    And it's possible to look what's there with:

    edid-decode /storage/.config/firmware/edid/edid-HDMI-A-1.bin

    I'm happy to receive edid files that cause a problem, but I think most issues are due to a lack of edid file.

    If the hdmi cable is missing hotplug, SCL or SDA lines (which cheap cables can do to save costs),

    then we can't read the edid.

    This issue can also be caused by the Argon One case which does a similar thing with cable extenders.

    Less common is a fault on display (worth trying different hdmi inputs, or a different display).


    You can run:

    Code
    edid-decode /sys/devices/platform/gpu/drm/card?/card?-HDMI-A-1/edid

    on a booted system (ssh in if display is blank). If you get lots of info about modes supported, then you have an edid.

    If you get an error, then we can't read the edid, and the only solution (apart from fixing the underlying issue) is editing config files.


    I think the simplest change to get a picture without an edid would be to add to end of cmdline.txt:

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

    (or some other resolution you know the display supports).


    But note, without an edid, kodi won't know the range of refresh rates supported (for "adjust display refresh rate to match video"), and CEC and audio passthrough are unlikely to work fully.

  • This issue can also be caused by the Argon One case which does a similar thing with cable extenders.


    Is this the case with all versions of the Argon One cases do you know? They switched from Micro-HDMI to Fullsize-HDMI on their Pi 4B cases - do both have issues with lack of Hotplug, SDA and SCL pass-through on their extenders?

  • Is this the case with all versions of the Argon One cases do you know? They switched from Micro-HDMI to Fullsize-HDMI on their Pi 4B cases - do both have issues with lack of Hotplug, SDA and SCL pass-through on their extenders?

    Ah, didn't know they now have fullsize HDMI, so there's some hope the situation improved.


    So far I only know about issues with their old micro HDMI versions. They had quite some QA / production issues with the board (can't say how high the actual failure rate was, though):

    - pin 19 (HPD) shorted to the GND/shield pad next to it, so hotplug detect didn't work

    - cold joints / no connection on some HDMI pins/pads


    So basically issues in their (reflow?) soldering process which OFC is more critical with the small pitch of micro HDMI connectors, compared to full size ones.


    Issues with soldering are quite common, it's very rare to hit 100% yield rate, but usually QA (automatic optical and electrical inspection systems) should have caught those.


    so long,


    Hias

  • That would explain an issue I've seen with one of my 4Bs in an Argon One case with Micro HDMI...

  • In have stopped using 2 of my 3 Argon cases, only using the very first one i bought for my PI3B+.