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Michael P

Hdmi out from zybo

Question

Hi,

I want to make a video processing ip on hdmi with Nexys Video. The hdmi signal will be generated by a Digilent Zybo board.

I took the prebuilt images from petalinux repo for zybo. The Linux boots and display the terminal on a regulator monitor.

Then, I connected the hdmi out from zybo to hdmi in port on nexys and monitor to nexys video hdmi out. For start, I just turned on the board with default configuratioin from qspi. The default configuration is a hdmi pass through because it works when I connect the input on nexys video to a raspberry pi. So,  the monitor should display the terminal, but it doesn't.

 

Taking a look at what dmesg prints, I've fount some interesting errors like:

Registering SWP/SWPB emulation handler
[    1.068461] [drm] No max horizontal width in DT, using default 1920
[    1.073394] [drm] No max vertical height in DT, using default 1080
[    1.078249] OF: graph: no port node found in /amba_pl/xilinx_drm
[    1.082930] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    1.088193] [drm] No driver support for vblank timestamp query.
[    1.099048] mmc0: new high speed SDHC card at address aaaa
[    1.103540] mmcblk0: mmc0:aaaa SC16G 14.8 GiB
[    1.108887]  mmcblk0: p1 p2
[    2.109425] cdns-i2c e0004000.i2c: timeout waiting on completion
[    2.114099] [drm] Cannot find any crtc or sizes
[    2.117637] [drm] Initialized xilinx_drm 1.0.0 20130509 for amba_pl:xilinx_drm on minor 0

Then, it prints continuously this:

 cdns-i2c e0004000.i2c: timeout waiting on completion
[   11.479277] cdns-i2c e0004000.i2c: timeout waiting on completion
[   11.483903] [drm] Cannot find any crtc or sizes
[   11.487524] [drm] Initialized xilinx_drm 1.0.0 20130509 for amba_pl:xilinx_drm on minor 0

What is wrong with it? How could I fix it?

On serial, the nexys video says : "Showing DVI input".

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10 answers to this question

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Try adding this:

&i2c0 {
	clock-frequency = <100000>;
	status = "okay";
};

Here: <petalinux_project>/project-spec/meta-user/recipes-bsp/device-tree/files/system-user.dtsi

-Ciprian

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I'm not sure about this but I would look in to the HPD signal, as far as I know in the Nexys Video demo is set up so that the HPD is a pass-trough signal which might interfere with the zybo z7 design. I will ask our colleague who has more experience in HDMI if he has some input regarding your question.

-Ciprian

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I believe the behavior is due to the Zybo Z7 Petalinux BSP wrongly using 400kHz on the DDC bus to read out the EDID. Nexys Video does not provide an intelligible answer in this case.

If you are in a hurry, try lowering the I2C0 speed to 100kHz. We will get around to fixing this eventually.

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Thank you for your answer! From where should I change the I2C0 frequency? From Zynq7 block? Because I haven't found any option to modify the frequency of i2c there, but most probably, I don't know where to look exactly.

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