No display on HDMI

[vbdasc]

Hello. I have a similar problem to all the others. I recently purchased an A20-Olinuxino-Micro and installed the latest Debian on it (2G Jessie release 11). But I cannot get my monitor working. It's a NEC LCD1970NX, connected to the board via a standard passive HDMI-DVI connector. U-Boot works with the monitor just fine, at its default resolution (1280x1024). But once the Linux kernel starts, display gets lost. I tried all available HDMI modes, and the aforementioned uEnv.txt trick, without success. The monitor has a valid 128-byte EDID block, I can post it here if necessary. The HDMI-DVI adapter has all necessary pins connected (three TMDS data channels, one TMDS clock channel, +5V, Hot Plug Detect, DDC Data/Clock/Ground, but no CEC/HEC/ARC). Any ideas? Thanks in advance.

[Gerrit]

did you already run the change display script ?

https://www.olimex.com/wiki/A20-OLinuXino-MICRO#How_to_change_HDMI.2C_VGA_and_LCD_resolutions_in_the_official_Debian_image.3F

maybe its on VGA or LCD now

[vbdasc]

did you already run the change display script ?

https://www.olimex.com/wiki/A20-OLinuXino-MICRO#How_to_change_HDMI.2C_VGA_and_LCD_resolutions_in_the_official_Debian_image.3F

maybe its on VGA or LCD now

Yes, and I tried all possible modes.

P.S. I've solved my problem (sort of). I had to modify boot.scr on the first partition to include kernel parameters disp.screen0_output_mode=EDID:640x480p60 hdmi.audio=EDID:0 , after which I finally got display at my default monitor resolution (1280x1024). Thanks everyone!

[vbdasc]

It turns out that the problem was caused by HDMI audio, or more specifically, the monitor's inability to support it. The monitor works when I specify the kernel parameter "hdmi.audio=EDID:0", which apparently disables HDMI audio on unsupported devices, and doesn't work without that parameter.

[msx_23]

I have the same problem with HDMI not working with Monitors that dont have speakers. I´m using the latest debian buster image with A20-LIME, but i don´t know exactly how to solve the problem... In U-boot the display works normal, but when Linux starts the Display goes into idle because of no signal, tested with 2 different displays that have no sound. With a monitor that has speakers there is no problem. Can someone please explain in more detail what are the steps to change the relevant kernel parameter to disable hdmi audio or how to patch a driver (if its the same for the latest buster image) as proposed in this thread:

https://www.olimex.com/forum/index.php?topic=4800.msg20005#msg20005

In the case I have to rebuild some drivers: Where are the correct sources for that and can I build them without rebuilding the whole Linux OS ( and just use insmod after building the module)

Or is there some other workaround?

Just appending "hdmi.audio=EDID:0" to the bootargs (at beginning or ending) has no effect

Edit: It is definetely a software problem: When I attach the "no-sound" monitor just after unplugging a "with-sound" monitor with Debian Jessie image the former also works, but after a reboot there is no signal on the "no-sound"monitors. On the Debian buster image the above trick does not work

Edit2: Appending "optargs=hdmi.audio=0" to /boot/uEnv.txt solves the issue for the standard image, but I replaced U-boot to disable the uboot-logs on hdmi and in that case HDMI still does not work at all on these "no-sound" monitors...

Edit3: The solution with hdmi.audio=0 only works with the official image "A20-OLinuXino-buster-base-20210318-122357.img", but as soon as i replace the U-boot (compiled with default settings) the HDMI gets lost when Linux boots, although it works in u-boot itself. Testet with own compiled u-boot versions 2021.01 (same as in the img-file) and 2021.04. Can you tell me what u-boot-settings you changed when compiling the official image compared to the github-repo "u-boot-olinuxino"?