Problems with HDMI display on Linux

[mmx-114514]

How to display via HDMI on linux system please? Is it by mounting the hdmi peripheral via liitex and then selecting the HDMI display related compilation options on buildroot, I tried to do this but it doesn't show up.

[Dolu1990]

Do you have it in the DTS ?

[mmx-114514]

It doesn't seem to be there. I selected hdmi via litex and I was able to see its constraints on the pins in .cst, but I can't find any configuration for hdmi in dts. Do I have to write my own documentation for this?

[Dolu1990]

ahhh curious, and is the HDMI displaying some random static noise when you boot ? Thing is for Digilent nexys video for example, if i remember well, the framebuffer was included in the dts by default

[mmx-114514]

Sorry, there is no output when HDMI is activated. I'm using Sipeed_tang_20k and the output dts file has nothing related to hdmi and hdmi has no output. I double-checked make.py in linux-on-litex-vexriscv to make sure that video_terminal was added, and re-executed make.py, and the .dts file still had no hdmi related configuration after compilation.

[Dolu1990]

Ahhh, i don't know much about that side of things. no hdmi output mean no hdmi signal at all ?

[mmx-114514]

Yes. I forgot to add the framebuffer xD. so far I solved the problem now I have the output of the linux terminal info. Thanks buddy.

[code11killer]

Yes. I forgot to add the framebuffer xD. so far I solved the problem now I have the output of the linux terminal info. Thanks buddy.

hello，I want to ask how to solve the problem. I meet the problem ，too

[mmx-114514]

code11killer
Add framebuffer to make.py

[code11killer]

code11killer
Add framebuffer to make.py

I add it to make.py. but I don't know how to output the video in my screen. beacuse I can't use the xrandr. Is there any other way? please

[code11killer]

code11killer
Add framebuffer to make.py

and after I add it，I also can't see the video in DTS. If it's convenient, can you add a contact information to talk about it?

[mmx-114514]

Ahhh, i don't know much about that side of things. no hdmi output mean no hdmi signal at all ?

Hello, I am experiencing a new problem, after introducing frame buffer output HDMI, the cpu performance is severely degraded, I have enabled --with-coherent-dma but the effect is not improved, I don't know how coherent-dma works here.

[mmx-114514]

Ahhh, i don't know much about that side of things. no hdmi output mean no hdmi signal at all ?

By the way, I currently implemented a terminal output text via HDMI on the display, and I would like to be able to display images, after adding the fbv related libraries in buildroot, cat /dev/urandom > /dev/fb0 can output garbled code normally with uart and HDMI, but I can't display the images with fbv (image), the error Displayed as: ?25lopen /dev/fb0: No such file or directory. and I can't find anything about framebuffer in DTS. I would like to know what I can do to make linux access the framebuffer for image display.