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Custom i.mx6ul/ull board; no display, ram test strangeness

Question asked by David Luberger on Sep 6, 2018
Latest reply on Sep 7, 2018 by David Luberger

I made a custom board based on the i.mx6ull evk.  I have successfully performed the RAM stress test, although I have some problems; for some reason, USB_OTG doesn't work. I copied what was done on the evk, but i'm getting the error in windows "unrecognized device". so from here on out, everything is done either by putting the SD card in jump drive or working via console and u-boot.

1.) I was able to run RAM stress test, but for some reason, I can't choose a DDR size bigger than 512 MB, even though my DDR is 4GB. I'm using DDR3L from ISSI part number IS43TR16256AL-125KBLI

2.) I still have a lot of work to do to get the device tree for linux modified for my hardware changes from the evk, but i have a new custom LCD; it's a 5" TFT at 800x480 resolution 24 bit RGB. I currently have just u-boot running on my sd card. How can I test the display without linux? I modified the u-boot code for my board to use the panel name "TFT50" with the correct resolution modified (was set for TFT43AB at 480x272), but right now my screen comes up blank because the LCD is being disabled. is there a way from the u-boot command line to set the backlight gpio to turn on the backlight, and then somehow display something on the screen? i thought there was a default image for the display while in u-boot and not booted into the OS, but like I said the display seems to be stuck off; I'm using GPIO5_IO9 like in the evk to enable/disable the LCD power supplies.  I can't find any documentation on using the u-boot gpio command and i don't know what name to call when using "gpio set" for GPIO5_IO9 to enable the LCD power and GPIO1_IO8 to enable the backlight (also the same as the evk board).

 

By the way, I'm not using yocto project for any of this because the documentation is so terribly convoluted; so I'm following other guides to manually configure and compile u-boot, the linux kernel, and different distros i'm trying to make work like debian linaro.  Right now i'm just focusing on hardware testing as much as i can through u-boot.

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