EDR capable <-> QDR capable link should come up at QDR.
EDR capable <-> EDR capable link should come up at EDR.
If EDR node talks to other EDR node across all EDR links, rate will be 100 Gbps (4x EDR).
When EDR node talks to QDR node, rate will be 40 Gbps (4x QDR).
When EDR node talks to other EDR node with intervening QDR link on path, rate will also be 40 Gbps.