Intel UHD770, Iris Xe DDC has problem

[mak_happy]

Hi everyone

I'm using Intel 12th CPU & internal GPU ( like UHD770, Iris Xe Graphics ).

But intel 12th GPU(UHD770, Iris Xe Graphics) has DDC problem.

When I connect UHD770 to 4k60 TV, GPU start DDC communication !

But DDC communication failed..

So, I checked DDC Signal(SCL, SDA) with oscilloscope.

( HDMI Receiver don't send i2c 'ACK' to Intel 'UHD770 & Iris Xe Graphics' )

1) 'SDA' signal go 'HIGH' - i2c START

2) 'SCL' signal go 'LOW'

3) delay about 120ns 

4) 'SDA' signal go 'HIGH'

But HDMI Receiver think '3) delay 120ns' is very small..

If HDMI Receiver use 'level shift(5V to 3.3V)' then delay more shorter(120ns -> 0ns)

Some HDMI Receiver judge '4) SDA signal go 'HIGH' is occurred early from '2) SCl signal go 'LOW'

so, HDMI Receiver think it to 'i2c STOP'

and HDMI Receiver don't send 'i2c ACK'

and Intel UHD770 & Iris Xe Graphics stop HDMI process & turn off HDMI video output.

Please help me.

[Jean_Intel]

Hello mak_happy,

Thank you for posting on the Intel️® communities. I am sorry to hear that you are experiencing issues with DDC communication between your devices.

In order to have a better understanding of your issue, please provide me with the following:

• When did the issue start?
• Are you using any type of adapter to connect your computer to the TV?
• What is the behavior of the issue? Do you have any display output from the TV?
• Does the issue changes depending on the resolution you select?
• Have you tried using a different display device?
• Is the issue present when using different video ports, for example, DP?
• Create a report using the following applications:

• Intel®️ System Support Utility (Intel®️ SSU) 
  • Download the Intel SSU
  • Open the application and click on "Scan" to see the system and device information. By default, Intel®️ SSU will take you to the "Summary View."
  • Click on the menu where it says: "Summary" to change it to "Detailed View."
  • To save your scan: click on "Next"; then "Save."

• Intel® Graphics Command Center:
  • Open the Intel Graphics Command Center
  • Navigate to the Support tab
  • Select System Diagnostic
  • Click Generate Report
  • Select Save and name the output file.

If you are having difficulty accessing DDC, please use the latest graphics driver. Our latest driver available at the moment is 31.0.101.3790, and to install the driver, I recommend you follow the Clean Driver Installation process.

Best regards,

Jean O. 

Intel Customer Support Technician

[mak_happy]

Dear Jean O.

Thank you for answer my problem.

I reply to below for your request.

1. When did the issue start?

 =>

[2022.11.23] My Customer Send e-mail "Redmi Book Pro 15(notebook) doesn't video with your 'HDMI receiver chip(MDIN640)' "

[2022.12.27] My another Customer Send e-mail "Intel Mini PC(NUC11PAH) doesn't video with your 'HDMI receiver chip(MDIN640)'"

[2022.01.03] My another Customer Send e-mail "Intel UHD770 Graphic Chip doesn't video with your 'MDIN receiver chip(MDIN640)"

So we start to debugging with 'intel UHD770 & Iris Xe Graphic Chip(intel 12th CPU internal GPU)'.

and then we found that 'intel UHD770 & Iris Xe Graphic Chip' has DDC problem with our 'HDMI receiver chip(MDIN640)'.

but intel 11'th graphic chips has no DDC problem with our 'HDMI receiver chip(MDIN640)'

So. we posted this issue in 'intel community'

2. Are you using any type of adapter to connect your computer to the TV?

=> we using 'HDMI receiver chip(MDIN640)'   [  PC  -  MDIN640(HDMI receiver + transmitter)  -  TV  ]

3. What is the behavior of the issue? Do you have any display output from the TV?

=> intel UHD770 & Iris Xe Graphic chips has DDC problem with 'HDMI receiver chip(MDIN640)'  when start to read EDID table.

and turn off hdmi output in 'intel UHD770 & Iris Xe Graphic chip'.

4. Does the issue changes depending on the resolution you select?

=> All resolution has same problem, because this is about DDC communication.

5. Have you tried using a different display device?

=> When we tested with LG TV,  test result is below

- HDMI 1-meter cable : o.k

- HDMI 5-meter cable : o.k

- HDMI 10-meter cable : n.g ( 20% fail occurred -- DDC Problem )

6. Is the issue present when using different video ports, for example, DP?

=> we are not have DP port in our 'HDMI receiver(MDIN640)'. 

Sorry we don't test it.

7. Create a report using the following applications:

=> we attached report file.

Thank you

Best regards.

Yang-yul Kim.

Macro Image Technology Inc.

[Jean_Intel]

Hello mak_happy,

Thank you for the information provided. 

I will proceed to check the issue internally and post back soon with more details.

Best regards,

Jean O. 

Intel Customer Support Technician

[Jean_Intel]

Hello mak_happy,

Thanks for waiting for a response.

Checking the information you share. You mentioned that the problem did not occur with different-length cables (1-meter or 5-meter); however, the issue is present with a 10-meter cable. Based on this information we can confirm that the issue is not caused by the Intel drivers, so you should contact the OEM to check the HDMI cables.

Since I recommended you contact the OEM. I will now proceed to close this thread to void confusion. If you need additional information, please submit a new question, as this thread will no longer be monitored.

Best regards,

Jean O.

Intel Customer Support Technician