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Switching fb0 and fb1 functionality

Question asked by jignesh patel on Jul 22, 2018
Latest reply on Aug 2, 2018 by jignesh patel

Hi All,


Processor : IMX6Q (MCIMX6Q6AVT10AD)

Linux Kernel : 4.9.11

Kernel reference : wandboard_imx_4.9.11_1.0.0_ga


  • We are making IMX6Q based product. In this product we are using 240x320 LCD.
  • Due to our requirement of displaying everything in Landscape mode we using IPU for rotation purpose. We took reference of patches available on thread ( )
  • In our application we are displaying GUI on fb0 and video fb1 layer.
  • Due to some visual appearance related issue we want to switch display on fb0 and fb1. Means we want to display video on fb0 layer and GUI on fb1 layer. 
  • When I tried to do in application video on fb0 layer looks very bad. (This application is using IPU_QUEUE_TASK API to reduce CPU overhead)
  • When I tried to use another application which uses VIDIOC_QBUF,  VIDIOC_DQBUF APIs (increase CPU overhead) instead of IPU task and uses video nodes (/dev/video16, /dev/video17 )  instead of fb nodes (/dev/fb0, /dev/fb1). Video looks good on both video nodes (/dev/vide016, /dev/video17)
  • My question is what is difference between displaying video on video node (/dev/vide016) and fb node (/dev/fb0). Please note that  on fb1 node I am able to display correct video. Also what is difference between displaying video on fb0 and fb1.
  • Do I have to do any extra configurations?

May be description looks little confusing so let me know if you have any questions or query or any more information is required from my side.