AudioMute_Flag May Be Set to 0 Before New Audio Timestamp and InfoFrame Packets Transmission

Based on the DisplayPort standard, the DisplayPort source device must set and maintain Vertical Blanking ID (VB-ID) bit 4 (AudioMute_Flag) at 1 until after the IP core transmits the new Audio Timestamp and Audio InfoFrame packets.

Altera DisplayPort TX designs configured to support audio may not comply to this rule. The DisplayPort IP core may set AudioMute_Flag back to 0 before sending a new and stable Audio Timestamp and Audio InfoFrame packets if the core is reset or when there is a change in the audio format, audio timing or link rate.

This issue may cause the IP core to transmit the new Audio Sample packet before the new Audio Timestamp and Audio InfoFrame packets.

There is no workaround for this issue.

This issue is fixed in version 16.0 of the DisplayPort IP core.