3.9.11. AM3 Beagle Bone Black Board ConfigurationΒΆ

AM335x has a HW bug, chapter 3.1.1 in the errata: “The blue and red color assignments to the LCD data pins are reversed when operating in RGB888 (24bpp) mode compared to RGB565 (16bpp) mode.” Therefore, the applications need to always use either 24 or 16 bpp modes, depending on the display HW connected to the board. The default pixel format XRGB8888 of the graphics application back ends and drivers within PSDK is not supported at the AM3 Beagle Bone Black Board where it is in 16bpp mode. To enable appropriate graphics display, make the following changes at various graphics related configuration files:

  • /etc/powervr.ini: add DefaultPixelFormat=RGB565
  • /etc/weston.ini: add gbm-format=rgb565 at section [core]
  • /etc/profile.d/qt_env.sh: add export QT_QPA_EGLFS_INTEGRATION=none

Another restriction of AM335x-based platform is that the width of display resolution must be multiple of 32. For example, 1360x768 will not work. The simple workaround is to specify the display resolution as one of the kernel boot parameters for non-Weston application and at /etc/weston.ini for Weston server. For example,

  • the following commands need to be executed at boot prompt
=> setenv optargs video=HDMI-A-1:1024x768
=> saveenv
  • add the HDMI-A configuration to /etc/weston.ini in a new “output” section, as shown below: