Custom display, IPU linux driver questions

[robertspriggs]

Hi,
We're using an iMX6DL and the board is based on the sabre design. It's an existing product, but so far we haven't made use of the VPU or IPU. We'd like to start streaming video out of the IPU into our FPGA. I'm using gStreamer and can decode a sequence of images from a video using imxvpudec and plug the output into imxipuvideosink. Reading back from /dev/fb0 I can see data is being written into the frame buffer, but hooking a scope to IPU DI pins shows no activity at all. We are using a custom linux build built by BuildRoot and uBoot. How do I go about configuring the display output of the IPU driver? (what files to edit etc.) OR am I going to have to write a new display driver and if so, is there an example of a custom display driver I can use for reference?

Note: changing the build system is not an option as this is an existing product with a very large code base.

[robertspriggs]

I get output from the display port right up until Linux loads, then the output dies before any drivers are started. I'm thinking it has to do with the device tree, but is there anything else it could be potentially?

[igorpadykov]

Hi Robert

for imxvpudec usage one can look at

trac.gateworks.com/wiki/Yocto/gstreamer

also one can try with nxp bsps and gstreamer plugins,

please check documentation included in linux doc bundle,

like linux user guide :

http://www.nxp.com/webapp/Download?colCode=L4.1.15_1.2.0_LINUX_DOCS&Parent_nodeId=133769948107170617... 

http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/?h=imx_4.1.15_1.0.0_ga

Best regards
igor
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[robertspriggs]

Hi Igor,

As I mentioned in the post, I have gStreamer and the IMX plugins already working. The problem is about custom displays. The video output of our iMX6 is going to an FPGA, but I'm seeing no action on the pins. I'm looking for info on how the DIs of the IPU are set up in the Linux display driver. At least that's what I think I'm looking for...

[igorpadykov]

Hi Robert

one can check AN3974 Different Display Configurations on i.MX35 Linux PDK

http://cache.freescale.com/files/dsp/doc/app_note/AN3974.pdf 

unfortunately I am not aware of similar documentation for newer kernels.

It may be useful to check attached Linux Manual, Chapter 6
Image Processing Unit (IPU) Drivers, for example driver for parallel lcd

mxc_lcdif.c from Table 6-1 and write own driver in similar way.

Community example of lvds lcd

https://community.freescale.com/thread/373763

Best regards
igor

[robertspriggs]

Thanks Igor,

I've started to read the display configurations document and It looks like it will answer a lot of questions.