HDMI_DDC_SDA_POL and HDMI_DDC_SCL_POL signals not AC coupled on carrier card

The OEM product design guide states that pins A34 and A35 are AC-Coupled on Carrier Board (eDP/DP) or Open-Drain, 1.8V (3.3V tolerant -DDC/I2C). This statement is on page 38 table 38. The schematic shows no capacitors in series with either pin A34 or A35. The device tree does not have either A35 or A35 set up as an open-drain I/O.

What is correct here? A35 and A34 are being used as I2C lines to the HDMI so I could not imagine that AC coupling these lines would be correct. The pin mux spread sheet shows these lines as requiring a 1K external pull up but the schematic has a 10K pull up. Can this be clarified?


Hi, as you can see in OEM DG, AC-coupled capacitors are necessary when A34/35 are used as eDP/DP port, and unnecessary when they are used as HDMI. It depends on your custom design.