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  1. Xilinx - All Programmable
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  3. AR# 47096: LogiCORE IP DisplayPort v2.3 - Why does the DisplayPort sink fail to complete an AUX to IIC (I2C) write that is greater than six bytes?

AR# 47096

LogiCORE IP DisplayPort v2.3 - Why does the DisplayPort sink fail to complete an AUX to IIC (I2C) write that is greater than six bytes?

Description

Why does the DisplayPort sink fail to complete an AUX to IIC (I2C) write that is greater than six bytes?

Solution

This is a known issue with the DisplayPort v2.1, 2.2, and 2.3 cores. This issue has been resolved in the DisplayPort v3.1 core.

To work around this issue, users will need to do the following using the write status command:


  1. Issue a Write Command (any length from 1 to 16)
  2. Irrespective of the response from Write (except NACK), issue a write_status with MOT command to the same device address.
  3. Repeat the same write_status command until a NACK response is received or until the number of bytes written is one less than the requested length.
  4. Issue a 1 byte EDID READ - this is a dummy command which will clear the state machine to IDLE state.
  5. Continue normal operations 


The Write to IIC (I2C) sequence must be as follows:
 
  1. Write Burst -> On NACK exit -> Else go to Step 2 ->
  2. Repeat Write Status with MOT until NACK is received or the number of bytes written is one less than the requested length to the same IIC (I2C)->
  3. Issue Read to EDID 1 byte ->
  4. Continue

Please see (Xilinx Answer 33258) for a detailed list of LogiCORE IP DisplayPort Release Notes and Known Issues.

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
33258 LogiCORE IP DisplayPort - Release Notes and Known Issues N/A N/A

Associated Answer Records

Answer Number Answer Title Version Found Version Resolved
44843 LogiCORE IP DisplayPort v2.3 - Does the DisplayPort I2C over AUX support clock stretching for slower I2C slaves? N/A N/A
AR# 47096
Date 08/11/2014
Status Active
Type General Article
IP
  • DisplayPort