Why does CvP not work correctly when using the Avalon-MM PCIe Hard IP?

Description

Due to a known issue in Quartus® II software releases v12.0SP2 and earlier, Configuration via Protocol (CvP) will not work correctly if Avalon® MM mode is being used.

Resolution

To work around this issue in software version v12.0SP2, modify the auto-generated Qsys top level RTL file to ensure that the following parameters are set:

.bypass_clk_switch_hwtcl                      ("false"),
.cseb_cpl_status_during_cvp_hwtcl        ("completer_abort"),
.core_clk_sel_hwtcl                              ("core_clk_250"),
.rx_ei_l0s_hwtcl                                   (0),
.enable_l0s_aspm_hwtcl                       ("false"),

This issue is fixed in version 12.1sp1 of the Quartus II software.