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No LiveVideo and /dev/fb0 when monitor unplugged from DP.

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Explorer
Posts: 169
Registered: ‎02-16-2014

No LiveVideo and /dev/fb0 when monitor unplugged from DP.

I got DiplayPort LiveVideo interface enabled, so I will get video data stream in PL for processing and output from PL to LVDS LCD panel. And everything works fine.

 

But if system boots without monitor - no /dev/fb0 appears until I plug monitor to DP and no video data coming from LiveVideo interface to PL (except clock which I get).

Plug - image on both monitor and LiveVideo, unplug monitor - no LiveVideo data.

 

How I can force/enable MaliGPU/FBDev to form image all the time - with or without monitor ?

 

 

Moderator
Posts: 281
Registered: ‎04-24-2017

Re: No LiveVideo and /dev/fb0 when monitor unplugged from DP.

Hi @fanat9,

 

Which release are you using? In 2018.1 DP driver supports hotplug

 

fbdev isn't initialized until the entire DRM pipeline is enabled.

 

If the lvds driver is implemented as a drm encoder driver, that will format the entire pipeline, and the fbdev will be initialized properly

if not, the drm core will see the pipeline as not complete, and fbdev emulation doesn't happen.

Thanks,
Sandeep
PetaLinux Yocto | Embedded SW Support

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Explorer
Posts: 169
Registered: ‎02-16-2014

Re: No LiveVideo and /dev/fb0 when monitor unplugged from DP.

[ Edited ]

Just switched to 2018.2

 

My design is just a PL converter/serializer of DP LiveVideo to LVDS based on XAPP1315 and I have to have it to work even if DP physically unplugged. I tried to pull DP_HPD_R line up and down, but it obviously failed to read EDID.

 

How I can force it always on? Its not possible to do thru devicetree?