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Scholar
Scholar
500 Views
Registered: ‎05-31-2012

ZynqMP DisplayPort Linux driver no support for YCBCR?

Hi, i'm trying to enable graphics for a Zynq MPsoc.

I have live video in YcbCr and live output in YCbCr. Graphics will be RGB. I enabled the converter inside DP.

In linux my application run Xorg, it modifies the output bringing back RGB output. I can't see any graphics.

I read in the driver page

https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842105/ZynqMP+DisplayPort+Linux+driver

that  12 bit YUV formats are not supported.

What doues this mean? that i cannot use output as YCbCr from DP when using linux?

That would make sense considering that i don' see the graphics.

Since i need an SDI video chain, i should then configure the DP to work in RGB and do the 444:422  RGB YCbCr outside right?

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Moderator
Moderator
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Registered: ‎11-09-2015

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

Hi @mrbietola 

The page only mentions that 12-bits YUV is not supported. But this still means that 6/8/and 10-bits YCbCr are supported.

Do you get any output with RGB?

Once again, you are in an unsupported usecase (using the live output without the PHY) so I am not sure what will be the behaviour of the driver


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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Scholar
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Registered: ‎05-31-2012

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

Hi @florentw ,

i make the graphics work with RGB, the problem was the xorg.conf config because the timing it uses must be the same of SDI (in my case for 1280x720@50Hz), not the timing for display port (DMT timing if i'm not wrong).

Anyway displayport live output is always 12 bits per component RGB or YCbCr(from the manual), if i configure everything rgb i have no problem (so live input, graphics and live output).

If i set llive video to YCbCr, when linux starts it reconfigures the output and i see wrong colors. So i would like to know if this is expected and if there is a gentle way to tell linux (or Xorg) that i use YCbCr. As an alternative, i'm thinking about configure the DP output after linux load overwriting the linux behaviour

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Registered: ‎11-09-2015

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

HI @mrbietola 

Sorry about the delay on this. Were you able to make any progress and find how to set the color space in linux?


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Scholar
Scholar
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Registered: ‎05-31-2012

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

i haven't tried yet, i was looking at thr device driver bindings, the old specifies the color space, maybe i can specify it also with the new.

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Registered: ‎11-09-2015

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

HI @mrbietola 

You will be able to change what clolor space you say you support, so setting YUV422 only might be a solution.

But I guess there should be another solution from linux side to set the default. But I do not have enough knowledge on linux for that...

@sandeepg 

Would you know how to set the default color space used by xorg for the displayport controller?

Thanks


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Scholar
Scholar
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Registered: ‎05-31-2012

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

@florentw  sorry if i tag you, i'm unable to find how can i pass the colorspace to the driver through device tree.

i see that in the old driver there are some clues, but in the newer i can't find them. I am unable to configure xorg properly to ycbcr too.

i need to set video input to ycbcr, set the live video blended output to ycbcr

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Scholar
Scholar
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Registered: ‎05-31-2012

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

any update on this?

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Registered: ‎11-09-2015

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

Hi @mrbietola 

Sorry I was on holiday the last 2 weeks.

I do not think it really make sense to have a specific color format defined in the device tree as it was done in the first version of the driver. Because the Displayport controller should support multiple color format at runtime. So I do not think setting the device tree is the way to go.

Did you try adding Option "ColorSpace" "YCbCr444" to your xorg.conf file?


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Scholar
Scholar
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Registered: ‎05-31-2012

Re: ZynqMP DisplayPort Linux driver no support for YCBCR?

i tried and it doesn't work

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