liumiao,
Sorry that it seems we have found the cause of this issue.
Could you try to change below fragment in porg/kernel-dts/tegra210-porg-p3448-common.dtsi?
Please change the “nvidia,xbar-ctrl” from <0 1 2 3 4> to <2 1 0 3 4> and then reflash your board.
148 };
149 sor1 {
150 /* Compared to Jetson-TX1's baseboard (P2597), HDMI TX
151 * lanes 0 and 2 have been swapped in Porg's baseboard
152 * (P3448) making it a straight lane mapping between
153 * SOR1 and the pad.
154 */
155 nvidia,xbar-ctrl = <0 1 2 3 4>;
156 status = "okay";
157 hdmi-display {
158 status = "okay";
159 };
160 };
You could check whether you correctly flash the dtb by using below command.
xxd /proc/device-tree/host1x/sor1/nvidia,xbar-ctrl