BeagleBone Black with Yocto and LCD Display

[aca94.f...@gmail.com]

Hi,

I am having trouble setting up LCD display for my project.

I am using BeagleBone Black and element14's 4.3'' LCD Display Cape (https://www.element14.com/community/docs/DOC-81966) for my master's thesis (Boot-time optimization). 

I am building the system using Yocto Project (Pyro version). I have built the system with bitbake (I set it up so that it builds for BBB, I am using meta-qt4 layer for Qt app, I set systemd as init_manager and i built the system using qt4e-demo-image recipe). 

All the complied files are copied to an SD card and system boots regularly, but there doesn't seem to be support for starting LCD screen. Additionally, the system doesn't start Qt-demo application which it is supposed to, but I suppose that is due to the LCD screen problem.

I have uEnv.txt file on root partition of the SD card (/boot folder), which looks like this:

#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0

uname_r=4.10.17-yocto-standard

#uuid=

#dtb=

###U-Boot Overlays###

###Documentation: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Overlays

###Master Enable

enable_uboot_overlays=1

###

###Overide capes with eeprom

#uboot_overlay_addr0=/lib/firmware/<file0>.dtbo

#uboot_overlay_addr1=/lib/firmware/<file1>.dtbo

#uboot_overlay_addr2=/lib/firmware/<file2>.dtbo

#uboot_overlay_addr3=/lib/firmware/<file3>.dtbo

###

###Additional custom capes

#uboot_overlay_addr4=/lib/firmware/<file4>.dtbo

#uboot_overlay_addr5=/lib/firmware/<file5>.dtbo

#uboot_overlay_addr6=/lib/firmware/<file6>.dtbo

#uboot_overlay_addr7=/lib/firmware/<file7>.dtbo

###

###Custom Cape

#dtb_overlay=/lib/firmware/<file8>.dtbo

###

###Disable auto loading of virtual capes (emmc/video/wireless/adc)

#disable_uboot_overlay_emmc=1

#disable_uboot_overlay_video=1

#disable_uboot_overlay_audio=1

#disable_uboot_overlay_wireless=1

#disable_uboot_overlay_adc=1

###

###PRUSS OPTIONS

###pru_rproc (4.4.x-ti kernel)

#uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-4-TI-00A0.dtbo

###pru_rproc (4.14.x-ti kernel)

uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-14-TI-00A0.dtbo

###pru_uio (4.4.x-ti, 4.14.x-ti & mainline/bone kernel)

#uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo

###

###Cape Universal Enable

enable_uboot_cape_universal=1

###

###Debug: disable uboot autoload of Cape

#disable_uboot_overlay_addr0=1

#disable_uboot_overlay_addr1=1

#disable_uboot_overlay_addr2=1

#disable_uboot_overlay_addr3=1

###

###U-Boot fdt tweaks... (60000 = 384KB)

#uboot_fdt_buffer=0x60000

###U-Boot Overlays###

cmdline=coherent_pool=1M net.ifnames=0 quiet

#In the event of edid real failures, uncomment this next line:

#cmdline=coherent_pool=1M net.ifnames=0 quiet video=HDMI-A-1:1024x768@60e

#Use an overlayfs on top of a read-only root filesystem:

#cmdline=coherent_pool=1M net.ifnames=0 quiet overlayroot=tmpfs

##enable Generic eMMC Flasher:

##make sure, these tools are installed: dosfstools rsync

#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh

but that doesn't seem to be enough to solve the problem. 

I am wondering what should be my next steps in order to make BBB notice that there is a cape, load dtb files and whatever else is necessary in order to start up the LCD screen. Am I supposed to add additional files (and which) to the root filesystem which was compiled? Am I supposed to set up Yocto in a different way so that it compiles the necessary files (e.g. there's no /lib/firmware at all currently)?

Thanks for any help,

Alexander.