Wandboard and Adafruit HDMI Display

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Wandboard and Adafruit HDMI Display

Postby jithcr » Wed May 25, 2016 7:13 am

Hello,

I am testing Adafruit 5" 800x480 HDMI display(https://learn.adafruit.com/adafruit-5-800x480-tft-hdmi-monitor-touchscreen-backpack/overview) with Android Kitkat prebuilt images and found display is not coming properly.I have confirmed that the HDMI display works fine with my Ubuntu PC.So the problem could be in boot parameters.
So I have modified uEnv.txt with "video_mode=display0=dev=hdmi0,mode=800x480@60,bpp=24" configuration.But again faced the same issue.

Below is the configuration check in serial console
root@wandboard:/ # cat /proc/cmdline
console=ttymxc0,115200 androidboot.console=ttymxc0 androidboot.hardware=freescale vmalloc=400M display0=dev=hdmi0,mode=800x480@60,if=RGB24,bpp=24

root@wandboard:/ # cat /sys/class/graphics/fb0/mode
S:720x480p-60
root@wandboard:/ # cat /sys/class/graphics/fb0/modes
S:1920x1080p-30
S:720x480p-60
S:720x576p-50
S:1280x720p-50
S:1920x1080p-50
S:1280x720p-60
S:1920x1080p-60
V:640x480p-60
D:1280x720p-60
D:1920x1080p-60
V:640x480p-60

How can I configure the Adafruit 5'' 800x480 HDMI display for Wandboard?
jithcr
 
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Re: Wandboard and Adafruit HDMI Display

Postby Tapani » Wed May 25, 2016 7:38 am

1. Can you check /proc/cmdline what the actual resolution parameter passed to the kernel is. Just to make sure :-)


2. Shouldn't 720x480 be supported by every HDMI compiant monitor?


3. I am afraid, that supporting a HDMI mode that aren't from the official CEA/DMT list of modes, you need to edit some source code.
(in case of old android, that would be inside the kernel, in file arch/arm/mach-mx6/board-wand.c)

Before going there, you could try giving the resolution without the frequency:
Code: Select all
display0=dev=hdmi0,mode=800x480,if=RGB24,bpp=24
Tapani
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Re: Wandboard and Adafruit HDMI Display

Postby jithcr » Wed May 25, 2016 8:10 am

Thank you for your quick response.

I have tried without the frequency and observed the same issue.

>> Can you check /proc/cmdline what the actual resolution parameter passed to the kernel is. Just to make sure.
Below mentioned is the proc entry
console=ttymxc0,115200 androidboot.console=ttymxc0 androidboot.hardware=freescale vmalloc=400M display0=dev=hdmi0,mode=800x480,if=RGB24,bpp=24 fbmem=y

>> 3. I am afraid, that supporting a HDMI mode that aren't from the official CEA/DMT list of modes, you need to edit some source code.
(in case of old android, that would be inside the kernel, in file arch/arm/mach-mx6/board-wand.c)


Also, I would like to inform that the same issue observed with the prebuilt Yocto and ubuntu images.
jithcr
 
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Joined: Wed May 25, 2016 6:04 am

Re: Wandboard and Adafruit HDMI Display

Postby Tapani » Wed May 25, 2016 10:23 am

Ok, can we try the following display parameter before considering re-compiling a kernel:
Code: Select all
display0=dev=hdmi0,timing=33260,800,210,46,1,480,22,23,1,if=RGB24,bpp=32


This does not use the automatic selection of timings by mode, but tries to force display timings.

Those timings work on two different 800x480 panels we have (on both LVDS and LCD interfaces, I've never tried to force HDMI timings before).
The timing parameters (afairc) are pixelclk,horiz-res,horiz-sync-width,horiz-front-porch,vert-res,vert-sync-width,horiz-back-porch,vert-front-porch,vert-back-porch.
Tapani
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Re: Wandboard and Adafruit HDMI Display

Postby jithcr » Wed May 25, 2016 10:48 am

Hi,

The above mentioned configuration is giving same issue with hdmi.

Its confirmed that the settings has been passed to kernel by giving the cat /proc/cmdline
root@wandboard:/ # cat /proc/cmdline
console=ttymxc0,115200 androidboot.console=ttymxc0 androidboot.hardware=freescale vmalloc=400M display0=dev=hdmi0,timing=33260,800,210,46,1,480,22 ,23,1,if=RGB24,bpp=32 fbmem=8M gpumem=64M expansion= baseboard=wand

With this timing parameters,the fb mode is got set to V:640x480p-60. :(
root@wandboard:/ # cat /sys/class/graphics/fb0/mode
V:640x480p-60
jithcr
 
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