Problem about SN65DSI86 SDP packet

Hello KL,

We are reviewing your question and we will reply in two days.

Regards,

Luis.

Hello KL,

if you check the Display Port spec ver. 1.2 you could see that describes this behavior in the page 51 section 2.2.1.1 Control Symbols for Framing: Default Framing Mode, it explains:

• BS (Blanking Start): For uPacket RX with a DPCD Revision of 1.2 or higher, the Enhanced Framing Mode described in the next section (Section 2.2.1.2) must be used when running in SST Mode. An upstream device interoperating with a downstream device with DPCD Revision of 1.2 or higher must enable Enhanced Framing Mode. In, the Blanking Start consists of a four symbol sequence on each lane.

o Inserted after the last active pixel during the vertical display period.

o Inserted at the same symbol time during vertical blanking period as during vertical display.

o This framing symbol must be periodically (every 213 or 8,192 symbols) inserted for active links with no main video stream data to send. In this condition, the BS symbol is immediately followed by VB-ID with its NoVideoStream_Flag set to 1. (For more information on VB-ID, refer to Section 2.2.1) This link symbol pattern is referred to as the “Idle Pattern”.

Regards,

Luis.

Hi,

1)      We agree that NoVideo flag (idle pattern) can be sent when there is no active video. However, during PSR entry, the SDP should be sent during active video (during the vertical blank)

This framing symbol must be periodically (every 213 or 8,192 symbols) inserted for active links with no main video stream data to send. In this condition, the BS symbol is immediately followed by VB-ID with its NoVideoStream_Flag set to 1. (For more information on VB-ID, refer to Section 2.2.1) This link symbol pattern is referred to as the “Idle Pattern”.

2)      It seems that when we send SDP packet via the generic command, the TI chip would stop the video, send out the SDP packet and resync to MIPI video for video resume.

3)      This SDP packet we are trying to send is the PSR entry SDP packet. When the video stop (inactive), the eDP TCON would insert black frame (based on the eDP spec), causing the black frame to be captured into the remote frame buffer as the static frame. Below is from eDP spec chapter 5, page 72

Note 1: The Sink must include the ability to automatically generate Black Video autonomously. The Sink must automatically enable Black Video under the following conditions:

i.      Upon LCDVCC power-on (within T2 max)

ii.      When the “NoVideoStream_Flag” (VB-ID Bit 3) is received from the Source (at the end of T9)

Thanks & Best Regards,

KL