VDMA vs Video FrameBuffer R/W IP Cores

[ziladdev]

Going through the documentation of both IP core, it seems these two cores functionality is overlapping. In our video application we wish to just buffer and push the video into DDR ram. Is it fair to assume that FrameBuffer Write is all we need? When do we need a full VDMA core?

[florentw]

Hi @ziladdev,

Yes both core have the samd functionality. You could do write only with the VDMA also.
However I recommend to use the frame buffer as it seems to slowly replace the VDMA (better for Linux, better performance...)

Regards

[florentw]

Hi @ziladdev,

If everything is clear for you, please kindly close the topic by marking a reply as accepted solution.

Thanks and Regards,

[ziladdev]

Thanks for the reply!

I have started using Video Frame Buffer instead of the VDMA, besides being a bit awkward. For instance, I had to pad the stream since for YUV422 it still expects 3x(8bits) components while my Video In to AXI4 spits outs 2x(8bits), this was clearly documented so no big deal.

One thing I noticed is that in terms of utilization it is using 2x DSP slices while VDMA uses none...I am wondering why would one need this for this function? I see the HLS logo on the actual block design and I was wondering if one had access to the (C/C++?) source code of the IP core ... (perhaps not!).

Anyways my design is quite heavy on the use of DSPs and It may happen that I will revert back to using VDMA...

Any views on this?

[bwiec · Accepted solution]

VDMA usage with MM2S disabled would be fine.

The Framebuffer read/write were written for VCU use cases in ZU+ devices because it expects specific format of the video data in memory.

[kieucua1503]

Hi biwec,

So, Can i use Video FrameBuffer with Zynq-7000? If yes, can you show me how?

I trying to use Video FrameBuffer Read + Video Mixer to driven ALI3 10inch from Avnet, built with Petalinux, xilinx drm driver initialize ok but I can't see any /dev/fbx on root file system.

Can you give me some suggestion for this?

Thanks and best regard,

[eramitverma1]

I am pretty new to this concept . can someone explain me when to use VDMA and when to use frame buffer write ?

So , what i understood is that we use VDMA when we have to support live streaming interface. 

and Support VDMA when simply store data in to DDR memory . 

if someone has more details please share. 

regards,

Amit Verma

[florentw]

HI @eramitverma1 

You might want to refer to the following AR as this is covering it:

AR#72543: When should I use the VDMA and when should I use the Video Frame Buffer?