The display we are using is a 1200x1920 portrait 7inch monitor. On top of the reference images, the only changes we have done is to change device tree overlay to the
When booting up the uboot message is correctly displayed, as soon as it hit this line the screen goes blank. mxc_sdc_fb fb@1: 1200x1920 h_sync,r,l: 8,120,72 v_sync,l,u: 23,63,39 pixclock=120004000 Hz. Not sure why it using the fb1.
However, when query the modes on the fb0, (cat /sys/class/graphics/fb0/modes), it listed two display as below, so I would think the 1200x1920 is supported.
We have tried manually set the mode by using
echo V:640x480p-60 > fb0/mode, it display correct content but only a 640x480 area is occupied. No surprise here. But when we set back to D:1200x1920 it goes blank with only backlight on it.
Full dmesg log is attached here, let me know if more information that could help to troubleshoot this issue. dmesg.txt (22.7 KB)
I have tried the setting video mode as following
setenv vidargs video=mxcfb0:dev=hdmi,1200x1920@60. It always fall back to 640x480
Here is something that may either be a message from Captain Obvious or fresh cheese from the stupid factory.
Isn’t the number after the “p” the supported refresh rate?
If so, you aren’t ever getting 60 to work at 1200x1920
I’m not a hardware guy so this may be speaking out my lower mouth, but when you look here:
Your board has both a VGA V: port and a DVI D: connector.
Frame buffer is a Linux specific thing. I’m not a driver guy or a kernel mod guy, but any frame buffer device can be mapped by any driver. Typically when you have “mirrored” displays they get mapped to the same frame buffer.
Just trying to help. Please take note of everything I’m not when evaluating the content.
We can see that fb0 didn’t find your display, but fb1 apparently found it and set the HDMI driver. I’m not sure why this is happening, but I think a good test would be trying to send the image from fb1 to fb0 and check what will happen.
Have you done any other modifications to your image?
Meanwhile, I’ll do some tests here on my side to see if I find something useful.
Other modification we have done is that we installed the dotnet layer on yocto. Could this possibly cause any issues to the framebuffer? We will try the default reference image from toradex to test if the problem still happens.
I want to update on this. We were able to get it working correctly now. It is strange since we fixed it by replacing a different HDMI Cable and now booting up and display screen properly. Dmesg still logged this message:
mxc_sdc_fb fb@1: 1200x1920 h_sync,r,l: 8,120,72 v_sync,l,u: 23,63,39 pixclock=120004000 Hz.
Neverthless it is good for now and thanks for all the help! It brings me another question that if there is any impact on the colibri hdmi adapter that could cause this?