AR# 73209

MIPI D-PHY v4.1: The minimum value of Tskewcal (Skew-Calibration Timing Parameter) for MIPI D-PHY IP

Description

Version 1.2 of the MIPI D-PHY specification states that the TSKEWCAL minimum value is 210 UI (1024 UI).

Is it possible to set the length of the periodic deskew pattern (TxSkewCalHS pulse length) to 1024 UI or 128 txbyteclockhs in the MIPI D-PHY TX IP?


 

Solution

The MIPI D-PHY TX IP can send a minimum length of 1024 UI or 128 txbyteclockhs for the periodic deskew-pattern.

Please note that the length of the periodic deskew pattern sent by the transmitter should match the requirement of the receiver side.

For example, if the user wants to do a MIPI D-PHY TX IP to MIPI D-PHY RX IP loopback test, the periodic deskew-pattern setting should be set to meet the MIPI D-PHY RX IP minimum requirement.

The MIPI D-PHY RX deskew algorithm requires a minimum of 8192 UI (or 1024 rxbyteclockhs) of periodic deskew-pattern to do calibration correctly.

Failure to meet the minimum requirement of 8192 UI for the periodic deskew-pattern can cause CRC errors to appear on the received HS long-packet.

Notes:

  1. The max physical skew on the board that can be removed is 1376ps
  2. For a system with physical skew up to 800ps , Periodic Deskew-Pattern Length should be set as 8192 UI (2^13 UI)
  3. For a system with physical skew up to 1376ps, Periodic Deskew-Pattern Length should be set as 16384 UI (2^14 UI)
  4. Even if the user sets a Periodic Deskew-Pattern Length longer than 2-14 UI, it will not improve the removable max physical skew of MIPI D-PHY RX.

Periodic Deskew-Pattern Length [UI]
Max physical skew which can be accurately removed during periodic calibration.
2^13
800ps
2^14
1376ps
2^15
1376ps

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
54550 LogiCORE IP MIPI D-PHY - Release Notes and Known Issues for the Vivado 2015.3 tool and later versions N/A N/A
AR# 73209
Date 04/15/2020
Status Active
Type Known Issues
Devices More Less
Tools
IP