SN65DSI86: AUX communication issues with USB-C convertors

Arturo Esteban Vazquez Gutierrez

Part Number: SN65DSI86
Other Parts Discussed in Thread: TEST2

Hello,

We are using the SN65DSI86 MIPI DSI to DisplayPort bridge for a custom implementation that follows the design shown below.

(Processor) -> (SN65DSI86) -> (USB-C connector) -> (USB-C to HDMI convertor) -> (monitor)

(Processor) -> (SN65DSI86) -> (USB-C connector) -> (USB-C to DisplayPort convertor) -> (monitor)

On our PCB the TEST2 pin of the SN65DSI86 is pulled high, and a Linux driver configures the bridge disabling the ASSR feature, there have been performed different tests using the following USB-C convertors:

(a) https://www.amazon.com/Digital-Multiport-Adapter-Nintendo-Portable/dp/B07JK9DFKH

(b) https://www.amazon.com/Belkin-Thunderbolt-Transfer-Upstream-Charging/dp/B07YLMJZXB

The only device that works correctly is (a) which completes the Link Training and displays image on several HDMI monitors.

When using the other two USB-C adapters (b and c) we have noticed AUX communication issues, using a USB-C Type C analyzer it can be seen those transactions are not acknowledged.

Is the bridge compatible with those USB-C convertors?

Which USB-C convertors can be used for this implementation?

Any information that you could provide us would be helpful.

Best regards,

Esteban V.

over 5 years ago

0 David (ASIC) Liu over 5 years ago

TI__Guru**** 176811 points

Esteban V.

Between the DSI86 and the Type-C connector, how do you MUX the DP signal over the Type-C?

Thanks

David

0 Arturo Esteban Vazquez Gutierrez over 5 years ago in reply to David (ASIC) Liu

Prodigy 200 points

Hi David,

Between the SN65DSI86 and the Type-C connector we have a cross bar switch (CBTL08GP053) and a redriver (PTN36502).

Thanks,

Esteban v.

0 David (ASIC) Liu over 5 years ago in reply to Arturo Esteban Vazquez Gutierrez

TI__Guru**** 176811 points

Esteban v.

1. From the screen capture, it looks like we successfully went into the DP alt mode. You could double check this by taking a look at the USB CC communication under the USB PD view tab.

2. How does the AUX/SBU switching being implemented on both sides of the Type-C? The DSI86 is sending the link training request out but the other side is not responding to the request. So the AUX/SBU is possibly not enabled or being switched incorrectly.

3. Do you have another Type-C source that will work with Sink 2 and 3? If you do, can we do a comparison?

Thanks

David

0 Arturo Esteban Vazquez Gutierrez over 5 years ago in reply to David (ASIC) Liu

Prodigy 200 points

Hello David,

Thank you for the quick response,

1.- Looking to the USB-C PD section it seems that the Altmode was correctly detected.

2.- For the USB-C negotiations we are using standard Linux drivers: https://elixir.bootlin.com/linux/v5.4.51/source/drivers/usb/typec

3.- Yes, we have tested the same set ups with a Samsung Galaxy Note 10, It is important to say that in our design when using the sink (a) the AUX transactions are correctly acknowledged and in the other hand the sink (c) didn’t give any reply, as shown on the following images:

Any information that you could provide us will be helpful.

Best regards,

Esteban V.

0 David (ASIC) Liu over 5 years ago in reply to Arturo Esteban Vazquez Gutierrez

TI__Guru**** 176811 points

Esteban V.

Can I take a look at the full log file?

Can you also measure the common mode voltage on AUXP/N and SBU1/2 between your design + sink C and Samsung Galaxy Note 10 + sink C? Are you seeing a difference in the common mode voltage?

Thanks

David

0 Arturo Esteban Vazquez Gutierrez over 5 years ago in reply to David (ASIC) Liu

Prodigy 200 points

Hi David,

Please find attached the complete Type-C analyzer captures for the sink (a), (b) and (c).

We are verifying if we can measure those signals.

By this time, is there other test that we can perform?

Thanks,

Esteban V.

typec_captures.zip

0 David (ASIC) Liu over 5 years ago in reply to Arturo Esteban Vazquez Gutierrez

TI__Guru**** 176811 points

Esteban V.

Before doing the AUX common mode voltage measurement, please see below DP alt mode flow. After the Discover Mode is successfully ACKed by the UFP_D, the DFP_D (your design) should be going into the ENTER Mode, but I don't see that in your capture.

Thanks

David

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SN65DSI86: AUX communication issues with USB-C convertors