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DisplayPort Sink Link Training Suggestions

5.2

Link Training Clock Recovery (CR) Phase

During link training, a DisplayPort 1.2 compliant source will follow the CR phase of link training detailed in

Figure 9. It is important the DisplayPort sink take full advantage of the source behavior. The state diagram

shows that CR phase will continue as long as the same VOD level is not used 5 times or a max VOD level

is never used. Because of this, the sink CR phase algorithm should never use the same voltage swing

level five times or the max voltage swing. Depending on the source, the max voltage swing level can be

either Level 2 or Level 3. Typically, a sink algorithm starts at level 0 and progress to level 3. It is

suggested to try level 0 two times, level 1 four times, level 2 four times, and level 3 once. Keep in mind

source support for level 3 is not required. For the case in which level 3 is not support by the source, level

2 will happen once.

Figure 9. DisplayPort 1.2a Link Training CR Phase State Diagram

13

SLLA358 – December 2015

DP159 as DisplayPort Retimer

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