i.mx8m HDMI problem

[a_bardi]

On a custom board equipped with an IMX.8 CPU I cannot make HDMI work. The issue is that upon insertion of HDMI cable and assertion of HDMI_HPD (high, 3.3V), the CPU does not start DDC communication with the Display on HDMI_DDC_SCL and HDMI_DDC_SDA pins. Internal HDMI supply (VDD_PHY1V8) is 1.8V stable. The Problem is not in the CPU module as HDMI works in its Development Kit.
Is there a way to check the status of HDMI_HPD pin? Wich register should I read?
Any help would be very much appreciated.

-Antonio-

[igorpadykov]

Hi Antonio

one can try to read "HPD input" in register HPD_PLUG_IN, described in

sect.13.4.10.1.77 HDMI HPD status (HPD_PLUG_IN)

i.MX 8M Dual/8M QuadLite/8M Quad Applications Processors Reference Manual

Custom board hdmi hardware may be checked using i.MX8M Hardware Developer’s Guide

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[a_bardi]

Igor,

thanks for your help. The Hotplug signal was correctly reaching the CPU, the problem was a wrong device tree configuration that failed to load the HDMI display configuration.

Thanks a lot,

best regards

-Antonio-