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Contributor
Contributor
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Registered: ‎01-27-2019

Can s2mm and mm2s in a VDMA be run absolutely independent of one another?

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with triple buffer,

hdmi in -> (dynamic slave s2mm) vdma (mm2s dynamic master) -> hdmi out

I let the hdmi in to stream for at least 5 seconds and then I unplug the hdmi in.  I expect that the hdmi out will show the last frame right before I unplug the hdmi in. Instead, it show a black screen. But why?

By unplugging the hdmi in, I expect that the s2mm will never be able to finish writing one of the triple buffer while mm2s will kept reading another one of the triple buffer repeatedly. Why did it show a black screen instead?

 

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Moderator
Moderator
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Registered: ‎11-09-2015

Hi @dr.elichan 

As per other topic (https://forums.xilinx.com/t5/Video-and-Audio/Simple-Question-on-VDMA-genlock-behaviour/td-p/1150778) it depends on the genlock configuration and if genlock is active or not.

But yes they can run independantly.

With that said, the case you are mentioning require that they do not run independently. Because the Read side needs to be aware of what was the last frame written


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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Moderator
Moderator
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Registered: ‎11-09-2015

Hi @dr.elichan 

As per other topic (https://forums.xilinx.com/t5/Video-and-Audio/Simple-Question-on-VDMA-genlock-behaviour/td-p/1150778) it depends on the genlock configuration and if genlock is active or not.

But yes they can run independantly.

With that said, the case you are mentioning require that they do not run independently. Because the Read side needs to be aware of what was the last frame written


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**

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Moderator
Moderator
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Registered: ‎11-09-2015

HI @dr.elichan 

Is everything clear for you on this?

Thanks,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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