topic Re: Using a QT4e app in yocto in i.MX Processors

Using a QT4e app in yocto

michaeldiamond — Wed, 18 Feb 2015 16:11:46 GMT

I have a qt 4 app that we have compiled and running on an LTIB version of our board.

Now after switching to yocto dizzy and the 3.10.17 kernel, I used the meta-toolchain-qte to compile our app. When I start the app in the application I get the following error continuously.

QScreenLinuxFb::connect: No such file or directory

Error opening framebuffer device /dev/fb0

....

I am trying to only include the necessary items in my image but here are the image recipes I am including.

inherit core-image

IMAGE_FEATURES += "ssh-server-openssh tools-debug"

IMAGE_FEATURES += "debug-tweaks"

IMAGE_INSTALL += "tzdata hostapd linux-firmware-wl12xx wpa-supplicant libusb1 libusb-compat bash openssh-sftp-server"

IMAGE_INSTALL += "qt4-embedded icu"

Am I missing something?

Any help would be appreciated.

Michael

Re: Using a QT4e app in yocto

michaeldiamond — Thu, 19 Feb 2015 18:35:35 GMT

Further information is I tried the qt4e-demo-image and the qte-in-use-image on the nitrogen6x board.

I get the same error on the serial console of the nitrogen board;

QScreenLinuxFb::connect: No such file or directory

Error opening framebuffer device /dev/fb0

QScreenLinuxFb::connect: No such file or directory

Error opening framebuffer device /dev/fb0

QScreenLinuxFb::connect: No such file or directory

Error opening framebuffer device /dev/fb0

QScreenLinuxFb::connect: No such file or directory

Error opening framebuffer device /dev/fb0

I don't have any files in the /dev that are fb0 or any other number. cat /proc/fb returns empty. I am not sure how to create a frame buffer. Doing this with the qt4 images also results in no FB files.

Does anyone have any info on this?

Re: Using a QT4e app in yocto

michaeldiamond — Tue, 24 Feb 2015 16:02:38 GMT

I got this working and hopefully can be helpful to others with similar issues. The problem had nothing to do with Qt. Both the X version and the embedded version did not work.

The main issue is that the bootloader needed to load a display. I did not have a display hooked up to the nitrogen6x board and it does not load a video if no screens are detected via i2c. Here are the args that worked for me.

setenv bootargs $bootargs video=mxcfb${nextcon}:dev=ldb,1024x600M@60,if=RGB666

screenres=1024,600

setenv fbmem ${fbmem},10M

My board has a display but we are currently not using it. To find out if you have any screens loaded type the command

cat /proc/cmdline

It will return something like the following;

enable_wait_mode=off video=mxcfb:dev=ldb,1024x600M@60,if=RGB666 video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off ,10M console=ttymxc1,115200 vmalloc=400M consoleblank=0 rootwait root=/dev/mmcblk0p2 mxc_hdmi.only_cea=1

Re: Using a QT4e app in yocto

SergioSolis — Wed, 11 Mar 2015 16:18:09 GMT

Thank you for posting the solution Michael, I'm sure it'll help other community members!