J784S4XEVM: rebuild dtd for updated device tree

Hi Shige,

Shige Wang said:

1. What is the steps to rebuild a device tree? The current device tree is in the prebuild Linux image coming with the SDK. 

Steps are here: https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-j784s4/11_00_00_08/exports/docs/linux/Foundational_Components_Kernel_Users_Guide.html#compiling-the-device-tree-binaries 

Shige Wang said:

2. Do we need to rebuild the kernel using yocto to rebuild the device tree?

No.

Shige Wang said:

3. Is there a way to adjust some configuration/parameters in current ti-dss driver for monitor (which works well) to support new display/monitor without rebuilding device tree? 

This is controlled by the display driver and EDID. tidss is the driver for the display subsystem (not the display). The changes to the device tree are necessary depending on what display you're using and its protocol. 

Also, please migrate to the 11.0 SDK if you are able to.

Best,
Jared

Hi Jared, 

Thanks for the response and the instructions.

Would you please further elaborate item 3? Which files in the yocto corresponding to the configuration of display driver? We have a 12" and 15" with 1920x720 resolution (HD). We need to get it working with Qt and gstreamer. A more detailed instruction on how to rebuild/modify the driver to support these displays would be much appreciated. 

If it works better to have a meeting or call for this. please let me know. Thanks.

Hi Shige,

Can you share what you are plugging the displays into?

The DP and HDMI resolution and framerate should be negotiated automatically.

Can you share the output of a modetest?

$ modetest -M tidss

Best,
Jared

Hi Jared, 

Sorry for the delayed response. Some other activities held me up from getting back to this issue.  

Now we got both displays working. It turned out that one display was not correctly connected (detected by modetest). After that fixed, we have both display working. 

With both displays working, we are trying to find how to control the content showing on each display. Referring to kmstest tool, it seems that we can do so either using device name or device file in /dev/dri. Is there some APIs, or config parameters, or sample code that is documented somewhere for us to refer for implementation? 

Thanks.

shige