No HDMI output with Topfoison 2k display

XCLR8

Mark Posted at 12/5/2017 14:23
Hello, I too have been experimenting with the TopFoison 2K display panel (with its HDMI board, so no ...

Mark it seems to me that it may be an audio issue Since my pc correctly idrntifies the panel as 2560x1440. reversing the orientation on firefly did not fix this.
I dont remember but I recall trying to force 1440x2560 through ADB to no success.

I believe the uboot or some config needs to be edited in order to bring the display online, but I am not sute where to look. Support has not been helpful.

Mark

Hi XCLR8,

according to the specification of the TopFoison 2k display panel, it has 2560 lines and each line has 1440 pixels. My PC nicely recognizes this as a "portrait" display (1440x2560). Of course, rotation function in Windows makes it possible to use it as a landscape oriented display.

If I look in the TRM document of the RK3399, there are two Video Output Processors (VOP_BIG, VOP_LITTLE). The VOP_BIG supports maximum output resolution of 4096x2160, VOP_LITTLE supports maximum resolution of 2560x1600. Consequently, the display requires more lines than the VOPs can deliver. For this reason, I can believe it will never work. I like to have this verified

However, would it be possible to have everything drawn 90 degrees rotated into the buffers? So internal buffers would require 2560x1440 buffers and just before going to the display (on the transmitter side, after the VOPs), rotate back. I don't know, I don't see any reference in the TRM that can do that.

Kind regards, Mark

XCLR8

I don't believe so.  I found documents that allow custom resolutions.  It is just a matter of compiling the correct system image out of that. I also don't see why VOP cannot be modified in a custom rims to allow more lines.

XCLR8

The problem is documentation on how to build those source files into a proper working image are poorly written and sparse.

Mark

So far I only found clues that indicate it will not work. I also can't find rotator-blocks that might circumvent the problem. And indeed, the documentation is very little. Custom resolutions are supported and modifications can be done, but you have to keep the maximum resolutions in mind that each HW-block has (in the chain to the display panel). As the image has to go thru the VOP and the HDMI transmitter, the VOP has a maximum on supported image size, which is smaller than required for the display (considering vertical direction then). I haven't found the maximum supported frame timings of the HDMI transmitter though.

XCLR8

I am not sure why there no reply from their eng team for this. Because it is quite a nice dev board. But they need to have more documentation on this.

I tried using the HDFury Integral to pull the timings, but had no luck, it is as though these settings are locked.