RGBA/ARGB LVDS output from i.MX6

[sharongolan]

Hi. I'm working with the i.MX6 with Yocto 1.5 "Dora" BSP.

In my setup the i.MX6 is required to output GUI as video with alpha-per-pixel values. The GUI is accelerated using OpenGL and the output I use is the LVDS. This LVDS output is connecte to an FPGA. The FPGA is responsible for blending of this GUI with incoming video. After blending (alpha-per-pixel) the FPGA conveys the blended result to screen.

My question is whether it is possible to output GUI with alpha values (some RGBA/ARGB/etc format) from the LVDS output? if this kind of output (video with alpha-per-pixel) is not available, is it possible to have some way/trick to enable it?

I'll appreciate any insights in general and any suggestions regrading possible solution (like changes in IPU/LVDS drivers, manipulation in GPU etc).

Thank you.

sharon

[igorpadykov]

Hi Sharon

I am afraid this is not possibe. Alpha-pixel values are used by

Combining Unit of DP but not outputted externally. For processing

one can look at sect.37.4.9.3 Combining Unit, 37.4.7.5.1 Bus Mapping Unit

IMX6DQRM and sect.4.11.10.4 IPU Display Interface Signal Mapping IMX6DQCEC

LDB (LVDS output) module just accepts these data for sending through lvds port.

Best regards

igor

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[sharongolan]

Thank you Igor. I really appreciate your quick reply.

Based on your direction I looked at the "Bus Mapping Unit" .I see that it's programmable. So it seems that I can try and set the the MD_OFFSET and  MD_MASK_ registers to build a RGBA666 24-bit from the RGBA8888 32-bit input. This way I can convey 24-bit with alpha value per-pixel to LDB (although I'll loose the 8-bit color depth and instead have 6-bit for R, G, B and alpha). Does this seem feasible to you ? is it expected to work ?

Thanks again.

sharon

[igorpadykov]

Hi Sharon

yes I think this is feasible with loss of some colour data.

~igor

[sharongolan]

Thank you igor.

I'll update when I'll have something new to share in this context.

Thanks. sharon.

[kekiefer]

Hi Sharon,

Apologies for the bump. I dug this thread researching the same possibility of outputting RGBA on the LVDS interface.

Were you ever able to get this to work?

Thanks,

Kurt