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Posts: 1
Registered: ‎06-27-2018
Location: US
Views: 171
Message 1 of 2

HDMI engineering assistance

I am not sure where exactly to post this or if such detailed engineering information is handlded in the forums. We have have had several Lenovo laptops (Carbon, X460, T460, etc.) when hooked to HDMI switchers or extenders, result with no audio. They are a combination of issues that leads to this behavior:
1. Lenovo running Windows are using the response from DDC slave address 0x81 to determine whether it is connected to a DVI (No audio) or HDMI (With audio). This is not according to the HDMI specification: According to the HDMI specification, the only valid method for the source to detect an HDMI sink is by searching for the HDMI vendor specific data block located in the EDID.
2. A device on the DDC bus is not responding correctly to slave address 0x80.


These fixes would, I assume require firmware updates and I am not sure if the issue resides on the Lenovo motherboard or the the video card, or if they are intergrated. If any one is familiar with such an issue, or if there is perhaps already a fix, your info would be much appricated.

Posts: 7,064
Registered: ‎09-03-2014
Location: SK
Views: 101
Message 2 of 2

Re: HDMI engineering assistance

Hello Dipdog21,


Sorry for not responding earlier, I've been discussing your post with engineers who will hopefully be able to provide an answer and need you to to clarify a couple of points for us please.


X460 is a typo and X260 was meant. Would it be possible for you to please post the full MTMs of the systems?  If CTO please provide sample serial numers for each system type by private message.

"when hooked to HDMI switchers or extenders" - there is an implication that you do not experience the issue when not connected to switchers or extenders i.e. directly attached to the notebooks' HDMI ports?

Are there any other harware components such as docking stations in play which also need to be taken into consideration.




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