[meta-freescale] U-Boot and Video Issues

Dan Riegsecker 1baldgeek at gmail.com
Fri Aug 10 10:32:46 PDT 2018

I'm working with an NXP SABRESD board which has an i.MX 6Q processor, 
building images with the Yocto Project, Sumo version. I am building the 
fsl-image-multimedia with the settings listed below. These images are 
being deployed to an SD card and boot from that SD card.

MACHINE ??= 'imx6qdlsabresd'
DISTRO ?= 'fslc-framebuffer'

The U-Boot that is being built is u-boot-fslc from 
https://github.com/Freescale/u-boot-fslc and branch 2018.07+fslc. I am 
not seeing the dynamically generated video_args being passed to the the 
kernel command line via the mmcargs U-Boot environment variable. When I 
examine the u-boot-fslc/include/configs/mx6sabre_common.h file I see the 
following at line 112.

"mmcargs=setenv bootargs console=${console},${baudrate} " \
	"root=PARTUUID=${uuid} rootwait rw\0" \
	VIDEO_ARGS "\0" \

Wouldn't the NULL termination at the end of "rootwait rw" have the 
effect of not allowing the VIDEO_ARGS to be appended to the mmcargs and 
therefore not appended to the bootargs? When I cat /proc/cmdline on the 
booted system, I do not see any video settings passed to the kernel.

Not seeing any video settings being sent to the kernel, I changed my 
mmcargs as listed below.

setenv mmcargs 'setenv bootargs console=${console},${baudrate} 
root=PARTUUID=${uuid} rootwait rw ${video_args}'

Now if I have a display connected the the HDMI port, I have tried two 
different displays, the kernel will not run and does not output 
anything, like a panic, over the serial console. When I boot the Sabre 
board with nothing plugged into the HDMI port the kernel loads and the 
video setting can be seen in /proc/cmdline. I am able to boot the NXP 
images, version imx-4.9.88-2.0.0_ga, with the same board and HDMI 
displays, having video working as expected. What would be causing the 
kernel to not load when an HDMI display is connected and video settings 
are passed to the the kernel via the command line, using only the 
Freescale community layers of Yocto?

Any advice or suggestions would be greatly appreciated.


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