Compiling kernel for fbdev and removing DRM support

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#1

Hi,

I would like to make a program that uses the fbdev to work and I need to compile the kernel to add this functionality and remove the DRM support.
I managed to compile a bootable kernel but I’m failing to get the fbdev working. I would like to know what is the easiest way to get the fbdev working.

The things that I modified to the kernel config are:

  • enable:
    CONFIG_FB_DA8XX=y
  • disable:
    CONFIG_DRM
    CONFIG_DRM_I2C_NXP_TDA998X
    CONFIG_DRM_TILCDC

What is missing to get video out with fbdev?

My board is a Beagleboard black wireless, and I couldn’t see any error on the dmesg or anything related to the video after booting without video. I’m compiling the kernel 4.14.108. I have an HDMI cable attached, but I’m also trying to get video out with an LCD cape (from farnell element14)

Thank you in advance for the help :slight_smile:

Best regards

#2

CONFIG_DRM_FBDEV_EMULATION

Then re-enable:

CONFIG_DRM
CONFIG_DRM_I2C_NXP_TDA998X
CONFIG_DRM_TILCDC

Regards,

#3

Hi Robert,

thank you for your message. I used the configuration from bb.org_defconfig and compiled again the kernel. I noticed that the default configuration enables CONFIG_DRM_FBDEV_EMULATION by default. I compiled the kernel, and I have video out to my LCD screen, but I still have problems with Retroarch to run on my board.

As this fbdev emulation is a default configuration I returned to the original kernel (4.14.71-ti-r80) and now I don’t really know why I cannot run Retroarch with the standard video support on my board.

I installed retroarch from the repository with (apt-get install retroarch) in a clean Debian 9.5 IOT image. I had video error problems, so I followed the instructions from here:

https://elinux.org/BeagleBoneBlack/SGX_%2B_Qt_EGLFS_%2B_Weston

to install the accelerated video driver, and I managed to get the 3D examples working nicely. But I still getting errors on the Retroarch log:

#4

Just to tell that I managed to run Retroarch (surprisingly well!!) on my board with the stock kernel. But only inside an X environment with SDL support (not SDL2) .

Best,