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Getting video in amlogic8726-m3

Note: This was originally posted on 25th March 2013 at http://forums.arm.com

Hi everyone

I'm working on an amlogic8726-m3 set tb box trying to get debian linux to run natvely.

I've managed to get a kernel running on a base root filesystem. But i'm not able to get anything on the screen except for the A9 logo.

I can play a movie with mplayer or vlc (command line versions based on directfb or sdl) and get audio thru the hdmi input of the tv. But the screen stays black with the A9 logo.

Same happens if I try to run Xorg with the generic fbdev driver (can't compile mali_drm required by X11 accelerated mali driver because of a kernel version mismatch).

Any help would be more than appreciated.

Thanks a lot!

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Pete over 11 years ago

Note: This was originally posted on 26th March 2013 at http://forums.arm.com

Hi Martin,

I don't think this has much to do with the Mali, but I have some ideas.

Being intended for the set top box (STB) market, the Amlogic system might have more than one framebuffer device, and may have some custom hardware to allow mixing of the multiple framebuffers (sometimes known as overlays).

Do you see anything in the kernel configuration about multiple framebuffers? What framebuffer device nodes are listed in the filesystem? You may find you can see which framebuffer you can draw to by doing something like:

cat /bin/sh > /dev/fb0 cat /bin/sh > /dev/fb1 cat /bin/sh > /dev/fb2

and see which (if any) produces output.

On other platforms I have seen that had an overlay mixer, there was a simple Linux command line utility to control the hardware and enable/disable framebuffers. You may need to search for some documentation on the chipset to learn if there is perhaps a memory mapped register you can read/write to control framebuffers.

Sorry I can't help more, you may be better off looking for a forum with more Linux or Amlogic knowledge for some of these questions.

HTH, Pete
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Pete over 11 years ago

Note: This was originally posted on 26th March 2013 at http://forums.arm.com

Hi Martin,

I don't think this has much to do with the Mali, but I have some ideas.

Being intended for the set top box (STB) market, the Amlogic system might have more than one framebuffer device, and may have some custom hardware to allow mixing of the multiple framebuffers (sometimes known as overlays).

Do you see anything in the kernel configuration about multiple framebuffers? What framebuffer device nodes are listed in the filesystem? You may find you can see which framebuffer you can draw to by doing something like:

cat /bin/sh > /dev/fb0 cat /bin/sh > /dev/fb1 cat /bin/sh > /dev/fb2

and see which (if any) produces output.

On other platforms I have seen that had an overlay mixer, there was a simple Linux command line utility to control the hardware and enable/disable framebuffers. You may need to search for some documentation on the chipset to learn if there is perhaps a memory mapped register you can read/write to control framebuffers.

Sorry I can't help more, you may be better off looking for a forum with more Linux or Amlogic knowledge for some of these questions.

HTH, Pete
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