Blank screen running Qt X11 app with Vivante

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Blank screen running Qt X11 app with Vivante

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Contributor IV

Hi everyone,

I've used Yocto dora to build a kernel (3.0.35 4.1.0 modified wandboard kernel) and filesystem (fsl-image-gui) for a custom board based on the i.MX6S.  When I run a Qt application on the board using startx ./my_application, the application runs but the screen is black.  Certain widgets will show once they are updated (ie. if I click on a checkbox), but everything else is black.

I tried modifying xorg.conf to use Driver "fbdev" instead of Driver "vivante", but then when I run the application I get an error saying no screens found.

Does anyone know what could cause this?


Thanks!

Marlon

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Contributor III

Marlon,

As a sanity check, your Xorg.conf should match one of the following cases:

_______________

1) Vivante driver:

Section "Device"

   Identifier  "i.MX Accelerated Framebuffer Device"

   Driver   "vivante"

   Option   "fbdev"   "/dev/fb0"

   Option   "vivante_fbdev" "/dev/fb0"

   Option   "HWcursor"  "false"

EndSection

Section "Screen"

   Identifier   "Default Screen"

   Device   "i.MX Accelerated Framebuffer Device"

EndSection

Section "ServerLayout"

   Identifier   "Default Layout"

   Screen   "Default Screen"

EndSection


_______________

2) fbdev:


Section "Device"

   Identifier  "Generic Framebuffer Device"

   Driver   "fbdev"

   Option   "fbdev"   "/dev/fb0"

   Option   "HWcursor"  "false"

EndSection

Section "Screen"

   Identifier   "Default Screen"

   Device   "i.MX Accelerated Framebuffer Device"

EndSection

Section "ServerLayout"

   Identifier   "Default Layout"

   Screen   "Default Screen"

EndSection



I would also recommend that you check /var/log/Xorg.0.log to see if there were any initialization errors that occurred at startup.

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Contributor IV

Thanks Justin, I've tried both of those xorg.conf configurations.  The first one gives me a blank screen (except for the mouse cursor), and the second one displays the app but the screen is corrupted when a new window is shown or the display is rotated.

Xorg.0.log does not show any errors.  There are a few warnings about missing fonts but that's it.

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Contributor IV

Ok I've been able to make some progress by adding xf86-video-fbdev to the bitbake image.  However now I have 2 new problems:

1. When video is played back, there are red dots that flicker in and out all over the screen (I'm using Gstreamer).

2. When I try to rotate the screen 180 degrees using <Option "Rotate" "CW"> in xorg.conf, there are black lines through the screen.

Can anyone help with these problems?

Thanks

Marlon

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