Cannot get display setup in dtb for HDMI with carrier

[kitnettles]

Hi, I’ve recently upgraded from a Jetson TX2 to an AGX Xavier using a connect-tech mimic on the existing TX2 carrier. All functions seems to work, except for HDMI output. The mimic supposed maps “HDMI0” to nothing, “HDMI1” to HDMI0 on the TX2 pinout, and “HDMI2” to HDMI1 on the TX2 pinout. It seems to me that the HDMI1 on the TX2 is mapped to the dev kit carrier’s hdmi port, so I’ve mapped head0 to sor2, which I presume is connected to HDMI2. I’ve also changed all the sor’s displays to hdmi ones. I’m still however not seeing any display output, or any recognition something is connected, which I presume is related to HPD? I’ve accidentally set up HPD on sor1, which lead to a display enumeration, but the same setup on SOR2, even connecting it to the same GPIOs by modifying the hdmi dtsi hasn’t yielded a connection. Any advice here would be great, thanks.

[WayneWWW]

Hi,

Just want to make sure if I understand the situation clearly. What is the exact thing you are doing here? Did you buy a board here and want to enable Xavier display? or you made this own carrier board?

Xavier and TX2 are not pin compatible. TX2 only has 2 external display heads/pins and Xaiver has 3.

I don’t think it is a good idea to keep using “tx2” as a sample to compare here and talking about how your pin is connected. You should directly tell how your Xavier pin is connected to these heads.

[kitnettles]

Hi,

I purchased a ConnectTech mimic, an adapter that converts the xavier mezzanine to the tx2-style mezzanine, and I am trying to use that adapter to adapt my AGX Xavier to my TX2 Development Kit. The problem is that my HDMI doesn’t work. I’m using the default pinmux currently (./flash jetson-agx-xavier-devkit mmcblk0p1) and I’ve slightly modified the DTB to make head0 on sor2, since the adapter connects hdmi1 on the tx2 side to sor2 on the xavier side. I’ve verified that HDMI_HPD, the output on the collector of Q507, is connected to L50 on the AGX Xavier, as is on the actual AGX Xavier Development kit. However, it seems probing HPD that it is stuck High (1.8v). Setting the HPD mask to high to bypass that leads to the bootloader thinking the hdmi is connected, but it promptly fails with i2c issues. I don’t know if this is due to bypassing some part of the connection flow or whether I2C is misconfigured as well. ConnectTech for their part seems to be disinterested in revealing the pinout of the mimic to fix this, despite marketing the mimic as compatible with any TX2 carrier.

I’m basically just looking for pointers on what the connection flow for hdmi should be and what I should be on the lookout for being misconfigured (5v HDMI regulators, I2C, etc).

Edit:
It appears my issue is related to the relocation of GPIOs from GPIO Expander #1 onboard to the Xavier, and that if I want to turn the HDMI 5v regulator on, I’d need to flip the 5V enable on on GPIO Expander #1 off I2C_GP1