AM625: GPU and Display Sub-system Overlay

Hi Mari,

I know the Linux Processor SDK doesn't provide DirectFB support. I am routing your other queries to our Graphics expert for comments.

Hi Bin,

Thanks for your reply. Looking forward to responses from the graphics experts.

-Mari

Hi Bin,

Do you have any updates from the graphics expert?

Sorry for the urgency, but being able to overlay at least three layers is key for this customer. If we can answer these questions for them, it would be very helpful for device selection.

Best regards,

Mari

Hi,

Any update on this?

Best,

Mari

Hi Mari,

Sorry for the delay, our graphics expert will be back to office next week. Please allow him a few days to catch up the work since he has been out for a few weeks.

Hi Mari,

In general, there isn't any limit on how many input images the GPU can read. However, your performance will vary based on the number of images read and their resolution/format. For example, reading a single 1080p image will be faster than multiple 1080p images. In your case, the GPU should be able to read 3 images and composite them into one output image. The GPU on AM625 is OpenGLES3.1 compliant and the customer can use standard Khronos API for composition. 

Regards,
Krunal

Hi Krunal,

Thanks for your response.

1. By the standard Khronos API, you mean the Open GL API correct?
2. Also, it seems from reading the AM62x Linux SDK documentation under 3.6.4 Display in the following link that the libdrm module is responsible for alpha blending and combining the overlays. Is this correct? 
   1. https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/08_03_00_19/exports/docs/linux/Foundational_Components/Graphics/Graphics_and_Display.html?highlight=opengl#display
3. Is there any examples or documentation specific about how to blend the composites that I can provide for the customer? (ie: https://docs.nvidia.com/jetson/l4t-multimedia/group__direct__rendering__manager.html)

Best,

Mari

Hi Mari,

1. Yes and just to clarify, it's OpenGL ES 3.1. 

2. The DSS IP supports alpha blending and composition. Please refer to the TRM for all the available feature set. 

3. Based on my discussion with developer, we don't have any DSS examples yet and I will file for an internal ticket. With regards to the GPU, the customer could just refer to online examples on Khronos website.

Regards,
Krunal

Hi Krunal,

Thanks for your response. Would you be able to provide more documentation on the libdrm module with regards to AM625x?

Best,

Mari

Hi Mari,

The libdrm module comes from the community and if you are interested in examples, please refer to the following:

1. https://github.com/tomba/kmsxx

2. https://github.com/freedesktop/mesa-kmscube

Regards,
Krunal