I’m very sorry to announce but Sadly, Our schematic design was wrong.
About HDMI DDC Line, we inverted CLK and DAT wrongly.
Correct connection.
HDMI_SCL DP2_AUX_CH_P I2C6_CLK
HDMI_SDA DP2_AUX_CH_N I2C6_DAT
Our Wrong connection in #37.
HDMI_SCL DP2_AUX_CH_N I2C6_DAT
HDMI_SDA DP2_AUX_CH_P I2C6_CLK
We modified the circuit and it works fine.
Sorry for misleading about HPD/DCE is not working.
Thank you for your patience and support.