Rasberry Pi 4 and No Signal on some monitors

loveridgem · November 25, 2020 at 1:59 AM

Hi,

New to Kodi and LibreELEC, not new to Linux. I purchased a Pi 4 to run Kodi on and I am really struggling with most monitors/TVs not detecting HDMI signal. I can unplug from one monitor at my desk to another and the display is fine. The monitor I'm using to get Kodi up does not work nor does the TV that I will eventually use. If I use my RPi3, the same monitor works fine.

This tells me:

the HW is working
the cable is good
LibreELEC and Kodi are up and running
the monitor is not the issue

I've made changes to the config.txt to force modes and hot plug, etc., but nothing is working and I need some more ideas. What more info would is needed to help me troubleshoot and solve this? I'm not seeing any errors in my log file other than freedesktop.UPower service file not existing. What tvservice output would be helpful, if any, for me to provide?

Thanks!

Mike

**Da Flex** · November 25, 2020 at 4:31 AM Official Post

Do you use HDMI 0 as RPi's output? If you use a case with HDMI wiring, remove the case.

PS: Did you already tried hdmi_safe=1 at config.txt?

loveridgem · November 25, 2020 at 11:19 PM

Hi Da Flex,

Thanks for responding.

Yes, I have tried hdmi_safe=1 and both HDMI sockets. I also have hdmi_force_hotplug=1. Even when the monitor shows no signal, I disconnect the cable from the monitor and connect it to a different monitor, it works fine. I'm guessing the monitor is not sending the right data to tell the Pi what mode to use.

Here is what tvservice -m CEA shows:

Code

# tvservice -m CEA
Group CEA has 9 modes:
           mode 1: 640x480 @ 60Hz 4:3, clock:25MHz progressive 
           mode 2: 720x480 @ 60Hz 4:3, clock:27MHz progressive 
           mode 3: 720x480 @ 60Hz 16:9, clock:27MHz progressive 
           mode 4: 1280x720 @ 60Hz 16:9, clock:74MHz progressive 
           mode 5: 1920x1080 @ 60Hz 16:9, clock:74MHz interlaced 
           mode 6: 720x480 @ 60Hz 4:3, clock:27MHz x2 interlaced 
           mode 7: 720x480 @ 60Hz 16:9, clock:27MHz x2 interlaced 
  (native) mode 16: 1920x1080 @ 60Hz 16:9, clock:148MHz progressive 
           mode 32: 1920x1080 @ 24Hz 16:9, clock:74MHz progressive

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Here is the status:

Code

tvservice -s
state 0xa [HDMI CUSTOM RGB lim 16:9], 1920x1080 @ 60.00Hz, progressive

I just did a tvservice -n and it shows the model number of the monitor that it's connected to. So there is communication.

Code

tvservice -n
device_name=VIZ-E241i-B1

I saw a page somewhere that I can't find anymore where I hardcoded modes and resolutions into config.txt and it didn't help. I don't know the tvservice command at all so I don't know if the output above is what's reported from the monitor or if it's what the Pi supports.

I am using a case that routes the ports to the back of the case, and I have tried direct connecting. Since it works on another monitor, then it must be something in how monitors are communicating with the Pi.

Other suggestions?

Thanks,

Mike

**Da Flex** · November 26, 2020 at 12:40 AM Official Post

Try this config.txt (enforces CEA mode 16):

Code

gpu_mem=320
force_turbo=0
hdmi_ignore_edid=0xa5000080
disable_overscan=1
framebuffer_width=1920
framebuffer_height=1080
hdmi_force_hotplug=1
hdmi_group=1
hdmi_mode=16
dtparam=audio=on
dtoverlay=vc4-fkms-v3d
max_framebuffers=2

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Those settings work for many users with older monitors.

loveridgem · November 26, 2020 at 2:32 AM

No joy on using the config you gave above.

I'm going to try Pi OS and maybe Pi Ubuntu to see if it's some odd driver issue. I see that this seems to be a common theme for Pi 4 users. I can try the official OS and if it doesn't work, I can follow the troubleshooting there. It may lead me to a solution for LE.

Thanks!

Mike

**Da Flex** · November 26, 2020 at 4:30 AM Official Post

One final thing, before I'm running out of ideas. Try different color spaces by editing hdmi_pixel_encoding at config.txt. Some monitors use YCbCr instead of RGB. Good luck!

loveridgem · November 26, 2020 at 7:24 PM

Yes, I'm at a complete loss on this. I'll try the color spaces later today.

What I have learned is the tvservice is returning the name of the monitor and its resolution. So there is communication and it should be showing me something. But I get nothing. Even during the basic boot to a new OS. I never see the Pi color splash before the OS loads.

I would think it was this one specific monitor, but it doesn't show on the TV either which would be CEA versus DMT. The fact it works on my Acer monitor leaves me scratching my head and really bummed the Pi 4 is having these issues.

**Da Flex** · November 26, 2020 at 7:38 PM Official Post

Quote from loveridgem

The fact it works on my Acer monitor leaves me scratching my head and really bummed the Pi 4 is having these issues.

Very rare, but possible. If my last advice doesn't work, I would go for a replacement.

cmoulliard · November 27, 2020 at 4:06 PM

I also experiment the same issue using a new Smart TV Philips 43UPS8505.

When Libreelec9.2.6 boots on Pi4, I only see on the TV the name `Kodi` next to the HDMI port 1 but nothing will be displayed and theTV finally reports "Please check the HDMI connection or HDMI parameters of the HDMI source. The cable is plugged to the HDMI port of a Pi4

Here is my config.txt

Code

# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2009-2014 Stephan Raue (stephan@openelec.tv)
# Copyright (C) 2016-present Team LibreELEC (https://libreelec.tv)
################################################################################
# Bootloader configuration - config.txt
################################################################################

################################################################################
# Memory (System/GPU configuration )
################################################################################

# Default GPU memory split - at least 288M is needed for some 4k HEVC files
gpu_mem=320

################################################################################
# For overclocking and various other settings, see:
# https://www.raspberrypi.org/documentation/configuration/config-txt.md
################################################################################
# Set 'force_turbo=1' to disable dynamic overclocking and enable overclocking always.
force_turbo=0

# Force HDMI even if unplugged or powered off
# hdmi_force_hotplug=1

# Doesn't sent initial active source message.
# Avoids bringing CEC (enabled TV) out of standby and channel switch when
# rebooting.
hdmi_ignore_cec_init=1

################################################################################
# End of default configuration
################################################################################

################################################################################
# Include distribution specific config file if it exists.
################################################################################
[all]
include distroconfig.txt

################################################################################
# HDMI
################################################################################
hdmi_safe=1
hdmi_force_hotplug=1
hdmi_group=1

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cmoulliard · November 27, 2020 at 4:53 PM

I resolved the problem I reported previously by switching the cable between the PI4 machine to another HDMI port as the one I chosen on the SmartTV was defined for another purpose. See this article for more information: HowTo: Enable video 4k@60Hz on Raspberry Pi 4 | Coding with Titans