SAMA5D4 xplained - HDMI from terminal

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Craig
Posts: 5
Joined: Wed Feb 20, 2019 6:21 am

SAMA5D4 xplained - HDMI from terminal

Wed Feb 20, 2019 6:30 am

Hi, my apologies in advance if this is too simple.
I just received my Xplained board today and I see that it appears to be pre-loaded with Yocto.
I would like to create a demo app that will do the following:
1 - create a framebuffer
2 - render a text file over the HDMI port
3 - decode a video H.264 and play it on the HDMI display

I see there are some demos but they seem to be rudimentary and support the LCD options.
And I don't see much support for the HDMI and video decoder.
Can anyone share their experience of steps that I should take to get these things working?
Many thanks!
blue_z
Location: USA
Posts: 1974
Joined: Thu Apr 19, 2007 10:15 pm

Re: SAMA5D4 xplained - HDMI from terminal

Thu Feb 21, 2019 1:16 am

Craig wrote: I would like to create a demo app that will do the following:
1 - create a framebuffer
2 - render a text file over the HDMI port
3 - decode a video H.264 and play it on the HDMI display
You will probably have to do more research before you can complete such an app.

Applications do not "create a framebuffer".
The framebuffer is a hardware device that requires kernel support, i.e. a driver.

The HDMI port is not accessible by an application program.
Output is not directed at the HDMI port like a serial port or Ethernet port.
The HDMI port continuously outputs rasterized data sourced from the framebuffer.

Study the SoC datasheet for the capabilities of the embedded video decoder (e.g. constraints on image size and frame rate).

Craig wrote: I see there are some demos but they seem to be rudimentary and support the LCD options.
And I don't see much support for the HDMI and video decoder.
What you'll find depends on which demo version you're looking at and where you look.
Linux kernel support has been spotty for both the Hantro video decoder in the SAMA5D4 and the SiI9022A HDMI encoder/transmitter installed on the board .

AFAIK the most recent kernel with both vdec and sii9022 support would be Linux 4.9-at91, which was used by Linux4SAM Demo 5.8.
You would need to boot the kernel on your board with the at91-sama5d4_xplained_hdmi.dtb file or install the demo image that's preconfigured for an HDMI display.

Regards
Craig
Posts: 5
Joined: Wed Feb 20, 2019 6:21 am

Re: SAMA5D4 xplained - HDMI from terminal

Sun Feb 24, 2019 7:59 am

Thanks for your kind reply.
I am making good progress in spite of obstacles at every turn.
This video helped me a lot...https://www.youtube.com/watch?v=5pronTeX0lo

One thing that helped was that I was able to load a pre-built image V6.0, and it was able to detect the display type after I moved R32 to R33.
By canceling boot sequence, then entering 'setenv display hdmi' and 'saveenv' it was able to get the demo screen working.
Next is to get control of the framebuffer so I'm on my way...

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