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multiple displays on var-som-mx6

Question asked by james payne on Apr 8, 2015

Hi,

 

I know this question has been asked a lot of times before for sabre lite etc and I've looked through those solutions but they don't seem to work. I've built a linux kernel and uboot from the current yocto git tree at variscite and then built  a buildroot filesystem.

 

All boots fine and does most things I want however I can't seem to get an output from either of the LVDS outputs HDMI works fine I even tried modifying the uboot video= parameters to match the ones at this variscite wiki page here:

 

http://variwiki.com/index.php?title=VAR-SOM-MX6_Yocto_Unit_Testing_V7

 

to see if that made any difference but still cannot get an an output from either LVDS display.

 

dmesg shows that the displays are all being detected as V4L devices but the hdmi is the only one given a higher level device node.

 

I'm also checking the display framebuffers by doing:

 

cat /dev/urandom > /dev/fbX (where x is the relevant framebuffer)

 

On framebuffer 0 it works every time with random noise displayed and then running out of memory on all other framebuffer there is no output on any other framebuffers.

 

my uboot parameters are video=mxcfb0:dev=hdmi,1280x720M@60,if=RGB24 video=mxcfb1:dev=ldb,800x480M@60,if=RGB666 screen_alternate=yes ldb=dul0

 

Any ideas where I'm going wrong?

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