IMX6Q dual cloned display (LVDS to HDMI)

[sergei_p]

Hello,

We need to support a mirrored output of a Qt application to LVDS and HDMI displays. The hardware platform is IMX6Q-based board. No Window Managers (X11 or Wayland), just plain Qt5 application. BSP version is 3.14.52.

By the kernel configuration. we already have /dev/fb0 for LVDS and /dev/fb2 for HDMI, and are able to output the graphics output to either LVDS or HDMI. Now we need to implement mirroring of LVDS to HDMI.

I've seen some suggestions (like to use a patch https://community.nxp.com/message/959332?commentID=959332#comment-959332?q=imx6q%20cloned%20displays ), but they are pretty old and I'm wondering if there is a solution already present in the current 4.14.78-based BSP?

Is such mirroring ever possible to implement on the IMX6Q hardware level, or should we look to implement mirroring in Qt?

Thanks!

Regards,

Sergei

[yyuan]

hi

i have the  same problem.  i want to display on lcd and  hdmi.i thank we are same.

have you sloved it?

please help me

tnank you

[Bio_TICFSL]

Hi Sergei,

Given that the IPU can't help solve the problem between HDMI and LVDS, we're stuck with implementing the mirroring. No with QT, The Vivante frame buffer driver does not put boin the X11 server. The Vivante frame buffer driver does not put both screens on the same X11 :display.screen (i.e., :0.0). It pth screens on the same X11 :display.screen (i.e., :0.0). It puts them on separate screens of the same display (in X11 parlance, :0.0 and :0.1). Because they are separate screens, the RANDR X11 server extension and the xrandr utility program won't help. But that's OK because before RANDR there was XINERAMA which can knit together separate screens on the same display.

After trying and failing to configure Xinerama for hours I came to the unpleasant discovery that the X11 server supported by the NXP 3.14.52-1.1.0 GA BSP does not support the Xinerama extension. Run "DISPLAY=:0 xdpyinfo" and you will also observe a lack of XINERAMA in the list of extensions. The /etc/X11/xorg.conf parser recognizes it but doesn't produce an error message.

Possibly you can use Xinerama to clone the HDMI and LVDS displays, but it will be necessary to first build your own X server.

Regards